our whole scope both in this and in all other occasions where like qualities are vrged is to prooue superfluous and ill grounded in nature and to be but meere termes to confound and leaue in the darke whosoeuer is forced to fly vnto them THE THERTEENTH CHAPTER Of three sortes of violent motion Reflexion Vndulation and Refraction THe motion we haue last spoken of because it is ordinarily either in part or wholy contrary to grauity which is accounted the naturall motion of most bodies vseth to be called violent or forced And thus you haue deliuered vnto you the natures and causes both of naturall and of forced motion yet it remaineth that we aduertise you of some particular kindes of this forced motion which seeme to be different from it but indeed are not As first the motion of reflexion which if we do but consider how forced motion is made we shall find that it is nothing else but a forced motion whose line wherevpon it is made is as it were snapped in two by the encounter of a hard body For euen as we see in a spoute of water that is strongly shott against a wall the water following driueth the precedent partes first to the wall and afterwardes coming themselues to the wall forceth them againe an other way from the wall right so the latter partes of the torrent of ayre which is caused by the force that occasioneth the forced motion driueth the former partes first vpon the resistent body and afterwardes againe from it But this is more eminent in light then in any other body because light doth lesse rissent grauity and so obserueth the pure course of the stroake better then any other body from which others do for the most part decline some way by reason of their weight Now the particular law of reflexion is that the line incident and the line of reflexion must make equall angles with that line of the resistent superficies which is in the same superficies with themselues The demonstration whereof that great witt Renatus Des Cartes hath excellently sett downe in his booke of Dioptrikes by the example of a ball strucken by a rackett against the earth or any resisting body the substance where of is as followeth The motion which we call vndulation needeth no further explication for it is manifest that since a pendant when it is remooued from its perpendicular will restore it selfe therevnto by the naturall force of grauity and that in so doing it gaineth a velocity and therefore can not cease on a suddaine it must needes be carried out of the force of that motion directly the coÌ„trary way vntill the force of grauity ouercoming the velocity it must be brought backe againe to the perpeÌ„dicular which being done likewise with velocity it must send it againe towardes the place from which it fell att the first And in this course of motion it must coÌ„tinue for a while euery vndulation being weaker then other vntill att last it quite ceaseth by the course of nature settling the ayre in its due situatioÌ„ according to the naturall causes that worke vpon it And in this very manner also is performed that vndulation which we see in water when it is stirred from the naturall situation of its sphericall superficies Galileo hath noted that the time in which the vndulations are made which follow one an other of their owne accord is the same in euery one of them and that as much time precisely is take vp in a pendants going a very short arch towardes the end of its vibration as was in its going of the greatest arch att the beginning of its motion The reason whereof seemeth strange to him and he thinketh it to be an accident naturall to the body out of its grauity and that this effect conuinceth it is not the ayre which mooueth such bodies Whereas in truth it is clearely the ayre which causeth this effect Because the ayre striuing att each end where it is furthest from the force of the motion to quiett it selfe getteth att euery bout somewhat vpon the space and so contracteth that into a shorter arch That motion also which we call Refraction and is manifest to sense onely in light though peraduenture hereafter more diligent searchers of nature may likewise find it in such other bodies as are called qualities as in cold or heate c. is but a kind of Reflexion for there being certaine bodies in which the passages are so well ordered with their resistances that all the partes of them seeme to permitt light to passe through them and yet all partes of them seeme to reflect it when light passeth through such bodies it findeth att the very entrance of them such resistances where it passeth as serue it for a reflectent body and yet such a reflectent body as hindereth not the passage through but onely hindereth the passage from being in a straight line with the line incident Wherefore the light must needes take a plye as beaten from those partes towardes a line drawne from the illuminant and falling perpendicularly vpon the resisting superficies and therefore is termed by mathematicians to be refracted or broken towardes the Perpendicular Now at the very going out againe of the light the second superficies if it be parallel to the former must needes vpon a contrary cause strike it the contrary way which is termed from the Perpendicular But before we wade any deeper into this difficulty we can not omitt a word of the manner of explicating refraction which Monsieur Des Cartes vseth so witty a one as I am sorry it wanteth successe He therefore following the demonstration aboue giuen of reflexion supposeth the superficies which a ball lighteth vpon to be a thinne linnen cloth or some other such matter as will breake cleanely by the force of the ball striking smartly vpon it And because that superficies resisteth onely one way therefore he inferreth that the velocity of the ball is lessened onely one way and not the other so that the velocity of its motion that way in which it findeth no resistance must be after the balles passage through the linnen in a greater proportion to the velocity which it hath the other way where it findeth resistance then it was before And therefore the ball will in lesse time arriue to its periode on the one side then on the other and consequently it will leane towardes that side vnto which the course wherein it findeth no opposition doth carry it Which to shâ—w how it is contrary vnto his owne principle lett vs conceiue the cloth CE to be of some thickenesse and so draw the line OP to determine that thicknesse And lett vs make from B vpon AL an other Parallelogramme like the Parallelogramme AL whose diameter shall be BQ And it must necessarilly follow that the motion from B to Q if there were no resistance were in the same proportion as from A to B. But the proportion of the motion from
an other forwardes as you may do a fine towel through a muskett barrell which though it be too limber to be thrust straight through yet cramming still new partes into it att the length you will driue the first quite through And thus when these partes of water are gott vp to the toppe of the vessell on which the filter hangeth and ouer it on the other side by sticking still to the towe and by their naturall grauity against which nothing presseth on this side the labell they fall downe againe by little and little and by droppes breake againe into water in the vessell sett to receiue them But now if you aske why it will not droppe vnlesse the end of the labell that hangeth be lower then the water I conceiue it is because the water which is all along vpon the flannen is one continued body hanging together as it were a thridde of wyre and is subiect to like accidents as such a continued body is Now suppose you lay a wyre vpon the edge of the basin which the filter resteth vpon and so make that edge the center to ballance it vpon if the end that is outermost be heauyest it will weigh downe the other otherwise not So fareth it with this thridde of water if the end of it that hangeth out of the pott that is to be filtred be longer and consequently heauyer then that which riseth it must needes raise the other vpwardes and fall it selfe downewardes Now the raising of the other implyeth lifting more water from the cisterne and the sliding of it selfe further downewardes is the cause of its conuerting into droppes So that the water in the cisterne serueth like the flaxe vpon a distaffe and is spunne into a thridde of water still as it commeth to the flannen by the drawing it vp occasioned by the ouerweight of the thridde on the other side of the center Which to expresse better by a similitude in a solide body I remēber I haue oftētimes seene in a Mercers shoppe a great heap of massy goldlace lye vpon their stall and a little way aboue it a round smooth pinne of wood ouer which they vse to hale their lace when they wind it into bottomes Now ouer this pinne I haue putt one end of the lace and as long as it hung no lower thē the board vpō which the rest of the lace did lye it stirred not for as the weight of the loose end carried it one way so the weight of the other side where the whole was drew it the other way and in this manner kept it in equilibrity But as soone as I drew on the hāging end to be heauyer thē the clymbing side for no more weigheth thē is in the ayre that which lyeth vpon the board hauing an other cēter then it began to roule to the ground and still drew vp new partes of that which lay vpon the board vntill all was tumbled downe vpon the floore In the same manner it happeneth to the water in which the thridde of it vpon the filter is to be compared fittly vnto that part of the lace which hung vpon the pinne and the whole quantity in the cisterne is like the bulke of lace vpon the shoppeboard for as fast as the filter draweth it vp it is conuerted into a thridde like that which is already vpon the filter in like manner as the wheele conuerteth the flaxe into yarne as fast as it draweth it out from the distaffe Our next consideration will very aptly fall vpon the motion of those thinges which being bent do leape with violence to their former figure whereas others returne but a little and others do stand in that ply wherein the bending of them hath sett them For finding the reason of which effects our first reflection may be to note that a superficies which is more long then broad containeth a lesse floore then that whose sides are equall or neerer being equall and that of those surfaces whose lines and angles are all equall that which hath most sides and angles containeth still the greater floore Whence it is that Mathematicians conclude a circle to be the most capacious of all figures and what they say of lines in respect of a superficies the same with proportion they say of surfaces in respect of the body contained And accordingly we see by consequence that in the making a bagge of a long napkin if the napkin be sowed together longwise it holdeth a great deale lesse then if it be sowed together broadwise By this we see plainely that if any body which is in a thicke and short figure be forced into a thinner which by becoming thinner must likewise become eyther longer or broader for what it looseth one way it must gett an other then that superfieies must needes be stretched which in our case is a Physicall outside or materiall part of a solide body not a Mathematicall consideration of an indiuisible Entity We see also that this change of figures happeneth in the bending of all those bodies whereof we are now enquiring the reason why some of them restore themselues to their originall figures and others stand as they are bent Then to begin with the latter sort we find that they are of a moist nature as among mettalls lead and tinne and among other bodies those which we account soft And we may determine that this effect proceedeth partly from the humidity of the body that standeth bent and partly from a drynesse peculiar to it that comprehendeth and fixeth the humidity of it For by the first they are rendred capable of being driuen into any figure which nature or art desireth and by the second they are preserued from hauing their grauity putt them out of what figure they haue once receiued But because these two conditions are common to all solide bodies we may conclude that if no other circumstance concurred the effect arising out of them would likewise be common to all such and therefore where we find it otherwise we must seeke further for a cause of that transgression As for example if you bend the bodies of young trees or the branches of others they will returne to their due figure It is true they will sometime leane towardes that way they haue beene bent as may be seene euen in great trees after violent tempestes and generally the heades of trees and the eares of corne and the growne hedgerowes will all bend one way in some countries where some one wind hath a maine predominance and raigneth most continually as neere the sea-shore vpon the westerne coast of England where the southwest wind bloweth constantly the greatest part of the yeare may be obserued but this effect proceeding from a particular and extraordinary cause concerneth not our matter in hand We are to examine the reason of the motion of Restitution which we generally see in yong trees and branches of others as we said before In such we see that the earthy part which maketh them stiffe or
to performe vitall motion pag. 203. § 1. The connexion of the following Chapters with the precedent ones ibid. § 2. Concerning seuerall compositions of mixed bodies pag. 204. § 3. Two sortes of liuing creatures pag. 205. § 4. An engine to expresse the first sort of liuing creatures ibid. § 5. An other engine by which may be expressed the second sort of liuing creatures pag. 207. § 6. The two former engines and some other comparisons applyed to expresse the two seuerall sortes of liuing creatures ibid. § 7. How plantes are framed pag. 209. § 8. How sensitiue creatures are formed pag. 210. CHAP. XXIV A more particular suruay of the generation of Animals in which is discouered what part of the animal is first generated pag. 213 § 1. The opinion that the seede containeth formally euery part of the parent ibid. § 2. The former opinion reiected pag. 214. § 3. The Authors opinion of this question pag. 215. § 4. Their opinion refuted who hold that euery thing containeth formally all thinges pag. 216. § 5. The Authors opinion concerning the generation of Animals declared and confirmed pag. 217. § 6. That one substance is changed into an other pag. 219. § 7. Concerning the hatching of chickens and the generation of other Animals pag. 220. § 8. From whence it happeneth that the deficiences or excrescences of the parents body are often seene in their children pag. 221 § 9. The difference betweene the Authors opinion and the former one p. 222 § 10. That the hart is imbued with the generall specifike vertues of the whole body whereby is confirmed the doctrine of the two former paragraphes pag. 223. § 11. That the hart is the first part generated in a liuing creature pag. 225. CHAP. XXV How a Plant or Animal cometh to that figure it hath pag. 226. § 1. That the figure of an Animal is produced by ordinarie second causes as well as any other corporeall effect pag. 226. § 2. That the seuerall figures of bodies proceed from a defect in one of â—he three dimensions caused by the concurrance of accidentall causes pag. 227 § 3. The former doctrine is confirmed by seuerall instances pag 228 § 4. The same doctrine applyed to Plantes pag. 229 § 5. The same doctrine declared in leafes of trees ibid. § 6. The same applyed to the bodies of Animals pag. 230 § 7. In what sense the Author doth admitt of Vis formatrix pag. 231 CHAP. XXVI How motion beginneth in liuing creatures And of the motion of the hart circulation of the bloud Nutrition Augmentation and corruption or death pag. 232 § 1. Fromwhence doth proceed the primary motion and growth in Plantes ibid. § 2. Monsieur des Cartes his opinion touching the motion of the hart p. 233 § 3. The former opinion reiected ibid. § 4. The Authors opinion concerning the motion of the hart pag. 234 § 5. The motion of the hart dependeth originally of its fibers irrigated by bloud pag. 236 § 6. An obiection answered against the former doctrine pag. 237 § 7. The circulation of the bloud and other effects that follow the motion of the hart pag. 238 § 8. Of Nutrition pag. 239 § 9. Of Augmentation pag. 240 § 10. Of death and sicknesse pag. 241 CHAP. XXVII Of the motions of sense and of the sensible qualities in generall and in particular of those which belong to Touch Tast and Smelling pag. 242 § 1. The connexion of the subsequent chapters with the precedent ibid. § 2. Of the senses and sensible qualities in generall And of the end for which they serue ibid. § 3. Of the sense of touching and that both it and its qualities are bodies 244 § 4. Of the tast and its qualities that they are bodies pag. 245 § 5. That the smell and its qualities are reall bodies ibid. § 6. Of the conformity betwixt the two senses of smelling and tasting p. 246 § 7. The reason why the sense of smelling is not so perfect in man as in beastes with a wonderfull historie of a man who could wind a sent as well as any beast pag. 247 CHAP. XXVIII Of the sense of hearing and of the sensible quality sound p. 249 § 1. Of the sense of hearing and that sound is purely motion ibid. § 2. Of diuers artes belonging to the sense of hearing all which confirme that sound is nothing but motion pag. 250 § 3. The same is confirmed by the effects caused by great noises pag. 251 § 4. That solide bodies may conueye the motion of the ayre or sound to the organe of hearing pag. 252 § 5. Where the motion is interrupted there is no sound ibid. § 6. That not only the motion of the ayre but all other motions coming to our eares make sounds pag. 253 § 7. How one sense may supply the want of an other ibid. § 8. Of one who could discerne sounds of words with his eyes pag. 254 § 9. Diuers reasons to proue sound to be nothing els but a motion of some reall body pag. 256 CHAP. XXIX Of Sight and Colours pag. 257 § 1. That Colours are nothing but light mingled with darkenesse or the disposition off a bodies superficies apt to reflect light so mingled ibid. § 2. Concerning the disposition of those bodies which produce white or blacke coulours pag. 259 § 3. The former doctrine confirmed by Aristotles authority reason and experience ibid. § 4. How the diuersity of coulours doe follow out of various degrees of rarity and density pag. 260 § 5. Why some bodies are Diaphanous others opacous pag. 261 § 6. The former doctrine of coulours confirmed by the generation of white and Blacke in bodies pag. 262 CHAP. XXX Of luminous or apparente Colours pag. 262 § 1. Apparitions of coulours through a prisme or triangular glasse are of two sortes ibid. § 2. The seuerall parts of the obiect make seuerall angles at their entrance into the prisme pag. 263 § 3. The reason why some times the same obiect appeareth throwgh the prisme in two places and in one place more liuely in the other place more dimme ibid. § 4. The reason of the various colours that appeare in looking throwgh a prisme pag. 264 § 5. The reason why the prisme in one position may make the colours appeare quite contrary to what they did when it was in an other position pag. 265 § 6. The reason of the various colours in generall by pure light passing through a prisme pag 266 § 7. Vpon what side euery colour appeareth that is made by pure light passing through a prisme pag. 267 CHAP. XXXI The causes of certaine appearances in luminous Colours with a conclusion of the discourse touching the senses and the sensible qualities pag. 268 § 1. The reason of each seuerall colour in particular caused by light passing through a prisme pag. 268 § 2. A difficult probleme resolued touching the prisme pag. 270 § 3. Of the rainebow and how by the colour of any body wee may know the composition of
light which two termes passe through all the bodies we haue notice of Therefore proceeding vpon our groundes before layed to witt that no body can be mooued of it selfe wee may determine those motions to be naturall vnto bodies which haue constant causes or percutients to make them alwayse in such bodies and those violent which are contrary to such naturall motions Which being supposed we must search out the causes that so constantly make some bodies descend towardes the center or middle of the earth and others to rise and goe from the center by which the world is subiect to those restlesse motions that keepe all thinges in perpetuall fluxe in this changeing sphere of action and passion Lett vs then begin with considering what effects the sunne which is a constant and perpetuall cause worketh vpon inferior bodies by his being regularly sometimes present and sometimes absent Obserue in a pott of water hanging ouer a fire how the heate maketh some partes of the water to ascend and others to supply the roome by descending so that as long as it boyleth it is in a perpetuall confused motion vp and downe Now hauing formely cōcluded that fire is light and light is fire it can not be doubted but that the sunne doth serue instead of fire to our globe of earth and water which may be fittly compared to the boyling pott and all the day long draweth vapors from those bodies that his beames strike vpon For he shooting his little darts of fire in multitudes and in continued streames from his owne center against the Python the earth we liue on they do there ouertake one an other and cause some degree of heate as farre as they sinke in But not being able by reason of their great expansion in their long iorney to conuert it into their owne nature and sett it on fire which requireth a high degree of condensation of the beames they do but pierce and diuide it very subtilely and cutt some of the outward partes of it into extreme litle atomes Vnto which they sticking very close and being in a manner incorporated with them by reason of the moisture that is in thē they do in their rebound backe from the earth carry them along with them like a ball that struck against a moist wall doth in its returne from it bring backe some of the mortar sticking vpon it For the distance of the earth from the sunne is not the vtmost periode of these nimble bodies flight so that when by this solide body they are stopped in their course forwardes on they leape backe from it and carry some litle partes of it with them some of them a farther some of them a shorter iorney according as their litlenesse and rarity make them fitt to ascend As is manifest by the consent of all authors that write of the regions of the ayre who determine the lower region to reach as farre as the reflexion of the sunne and conclude this region to be very hoat For if we marke how the heate of fire is greatest when it is incorporated in some dense body as in iron or in seacoale we shall easily conceiue that the heate of this region proceedeth mainely out of the incorporation of light with those litle bodies which sticke to it in its reflexion And experience testifyeth the same both in our sultry dayes which we see are of a grosse temper and ordinarily goe before raine as also in the hoat springes of extreme cold countries where the first heates are vnsufferable which proceede out of the resolution of humidity congealed and in hoat windes which the Spaniards call Bochornos from Boca de horno by allusion to the breathing steame of an ouen when it is opened which do manifestly shew that the heate of the sunne is incorporated in the litle bodies which compose the steame of that wind And by the principles we haue already layed the same would be euident though we had no experience to instruct vs for seeing that the body of fire is dry the wett partes which are easilyest resolued by fire must needes sticke vnto them and accompany them in their returne from the earth Now whiles these ascend the ayre must needes cause others that are of a grosser complexion to descend as fast to make roome for the former and to fill the places they left that there may be no vacuity in nature And to find what partes they are and from whence they come that succeede in the roome of light and atomes glewed together that thus ascend we may take a hinte from the maxime of the Optikes that light reflecting maketh equall angles whence supposing the superficies of the earth to be circular it will follow that a perpendicular to the center passeth iust in the middle betweene the two rayes the incident and the reflected Wherefore the ayre betweene these two rayes and such dodies as are in it being equally pressed on both sides those bodies which are iust in the middle are neerest and likelyest to succeede immediately in the roome of the light and atomes which ascend from the superficies of the earth and their motion to that point is vpon the perpendicular Hence it is euident that the ayre and all such bodies as descend to supply the place of light and atomes which ascend from the earth do descend perpendicularly towardes the center of the earth And againe such bodies as by the force of light being cutt from the earth or water do not ascend in forme of light but do incorporate a hidden light and heate within them and thereby are rarer then these descending bodies must of necessity be lifted vp by the descent of those denser bodies that goe downewardes because they by reason of their density are mooued with a greater force And this lifting vp must be in a perpendicular line because the others descending on all sides perpendicularly must needes raise those that are betweene them equally from all sides that is perpendicularly from the center of the earth And thus we see a motion sett on foote of some bodies continually descending and others continually ascending all in perpendicular lines excepting those which follow the course of lights reflexion Againe as soone as the declining sunne groweth weaker or leaueth our horizon and that his beames vanishing do leaue the litle horsemen which rode vpon them to their owne temper and nature from whence they forced them they finding themselues surrounded by a smart descending streame do tumble downe againe in the night as fast as in the day they were carryed vp and crowding into their former habitations they exclude those that they find had vsurped them in their absence And thus all bodies within reach of the sunnes power but especially our ayre are in perpetuall motion the more rarifyed ones ascending and the dense ones descending Now thē because no bodies wheresoeuer they be as we haue already shewed haue any inclination to moue towardes a particular place otherwise thē as they are
fro And taking a body of concaue surfaces we shall according to this doctrine of ours find the causes of refraction iust contrary and accordingly experience likewise sheweth vs the effects to be so too And therefore since experience agreeth exactly with our rules we can not doubt but that the principles vpon which we goe are well layd But because crooked surfaces may haue many irregularities it will not be amisse to giue a rule by which all of them may be brought vnto a certainety And this it is that reflexions from crooked superficieses are equall to the reflexions that are made from such plaine superficieses as are tangents to the crooked ones in that point from whence the reflexions are made Which principall the Masters of Optikes do take out of a Mathematicall supposition of the vnity of the reflecting point in both the surfaces the crooked and the plaine But we take it out of the insensibility of the difference of so litle a part in the two different surfaces as serueth to reflect a ray of light for where the difference is insensible in the causes there likewise the difference is so litle in the effects as sense can not iudge of them which is as much as is requisite to our purpose Now seeing that in the Mathematicall supposition the point where the reflexion is made is indifferent to both the surfaces it followeth that it importeth not whether superficies you take to know the quality of reflexion by This principle then being settled that the reflexion must follow the nature of the tangent surfaces and it being prooued that in plaine surfaces it will happen in such sort as we haue explicated it followeth that in any crooked superficies of what figure soeuer the same also will happen Now seeing we haue formerly declared that refractions are but a certaine kind of reflexions what we haue said here of reflexions may be applyed to refractions But there remaineth yet vntouched one affection more of refractions which is that some diaphanous bodies do in their inward partes reflect more then others which is that which we call refraction as experience sheweth vs. Concerning which effect we are to consider that diaphanous bodies may in their composition haue two differences for some are composed of greater partes and greater pores others of lesser partes and lesser pores It is true there may be other combinations of pores and partes yet by these two the rest may be esteemed As for the first combination we see that because the pores are greater a greater multitude of partes of light may passe together through one pore and because the partes are greater likewise a greater multitude of rayes may reflect from the same part and may find the same passage quite throughout the diaphanous body On the contrary side in the second combination where both the pores and the partes of the diaphanous body are litle the light must be but litle that findeth the same passage Now that refraction is greater or lesser happeneth two wayes for it is eyther when one diaphanous body reflecteth light att more angles then an other and by consequence in a greater extent of the superficies or else when one body reflecteth light from the same point of incidence in a shorter line and in a greater angle then an other doth In both these wayes it is apparant that a body composed of greater partes and greater pores exceedeth bodies of the opposite kind for by reason that in the first kind more light may beate against one part a body in which that happeneth will make an appearance from a further part of its superficies whereas in a body of the other sort the light that beateth against one of the litle partes of it will be so litle as it will presently vanish Againe because in the first the part att the incidence is greater the surface from which the reflexion is made inwardes hath more of a plaine and straight superficies and consequently doth reflect att a greater angle then that whose superficies hath more of inclining But we must not passe from this question without looking a litle into the nature of those bodies in which refraction is made for if they as well as the immediate causes of refraction do likewise fauour vs it will not a litle aduance the certainety of our determination To this purpose we may call to mind how experience sheweth vs that great refractions are made in smoake and in mistes and in glasses and in thicke bodied waters and Monsieur Des Cartes addeth certaine oyles and spirits or strong waters Now most of these we see are composed of litle consistent bodies swimming in an other liquide body As is plaine in smoake and mistes for the litle bubbles which rise in the water before they gett out of it and that are smoake when they gett into the ayre do assure vs that smoake is nothing else but a company of litle round bodies swimming in the ayre and the round consistence of water vpon herbes leafes and twigges in a rynde or dew giueth vs also to vnderstand that a mist is likewise a company of litle round bodies that sometimes stand sometimes floate in the ayre as the wind driueth them Our very eyes beare wittnesse to vs that the thicker sort of waters are full of litle bodies which is the cause of their not being cleare As for glasse the blowing of it conuinceth that the litle dartes of fire which pierce it euery way do naturally in the melting of it conuert it into litle round hollow bodies which in their cooling must settle into partes of the like figure Then for crystall and other transparent stones which are found in cold places it can not be otherwise but that the nature of cold piercing into the maine body and contracting euery litle part in it selfe this contraction must needes leaue vacant pores betweene part and part And that such transparent stones as are made by heate haue the like effect and property may be iudged out of what we see in brickes and tiles which are left full of holes by the operation of the fire And I haue seene in bones that haue layne a long time in the sunne a multitude of sensible litle pores close to one an other as if they had beene formerly stucke all ouer with subtile sharpe needles as close as they could be thrust in by one other The Chymicall oyles and spirits which Monsieur Des Cartes speaketh of are likely to be of the same composition since that such vse to be extracted by violent fires for a violent fire is made by the coniunction of many rayes together and that must needes cause great pores in the body it worketh vpon and the sticking nature of these spirits is capable of conseruing them Out of all these obseruations it followeth that the bodies in which greatest refractions do happen are compounded as we haue said of great partes and great pores And therefore by onely taking light to be
meanes she vseth to auoyde it For to putt it as an enemy that nature fighteth against or to discourse of effects that would follow from it in case it were admitted is a great mistake and a lost labour seeing it is nothing and therefore can do nothing but is meerely a forme of expression to declare in short nothing else but that it is a contradiction or implication in termes and an impossibility in nature for vacuity to haue or to be supposed to haue a Being Thus then since in our case after we haue cast all about we can pitch vpon nothing to be considered but that the two stones do touch one an other and that they are weighty we must apply our selues onely to reflect vpon the effects proceeding from these two causes their contiguity and their heauynesse and we shall find that as the one of them namely the weight hindereth the vndermost from following the vppermost so contiguity obligeth it vnto that course and according as the one ouercometh the other so will this action be continued or interrupted Now that contiguity of substances do make one follow an other is euident by what our Masters in Metaphysickes teach vs when they shew that without this effect no motion att all could be made in the world nor no reason could be giuen for those motions we dayly see For since the nature of quantity is such that whensoeuer there is nothing between two partes of it they must needes touch and adhere and ioyne to one an other for how should they be kept asunder when there is nothing betweene them to part them if you pull one part away eyther some new substance must come to de close vnto that which remoueth or else the other which was formerly close to it must still be close to it and so follow it for if nothing do come between it is still close to it Thus then it being necessary that something must be ioyned close to euery thing vacuity which is nothing is excluded from hauing any being in nature And when we say that one body must follow an other to auoyde vacuity the meaning is that vnder the necessity of a contradiction they must follow one an other and that they can not do otherwise For it would be a contradiction to say that nothing were between two thinges and yet that they are not ioyned close to one an other And therefore if you should say it you would in other wordes say they are close together and they are not close together In like manner to say that vacuity is any where is a pure contradiction for vacuity being nothing hath no Being att all and yet by those wordes it is said to be in such a place so that they affirme it to be and not to be att the same time But now lett vs examine if there be no meanes to auoyde this contradiction and vacuity other then by the adhesion and following of one body vpon the motion of an other that is closely ioyned to it and euery where contiguous For sense is not easily quieted with such Metaphysicall contemplations that seeme to repugne against her dictamens and therefore for her satisfaction we can do no lesse then giue her leaue to range about and cast all wayes in hope of finding some one that may better content her which when she findeth that she can not she will the lesse repine to yield her assent to the rigourous sequeles and proofes of reason In this difficulty then after turning on euery side I for my part can discerne no pretence of probability in any other meanes then in pulling downe the lower stone by one corner that so there may be a gaping between the two stones to lett in ayre by little and little And in this case you may say that by the interuention of ayre vacuity is hindered aud yett the lower stone is left att liberty to follow its owne naturall inclination and be gouerned by its weight But indeed if you consider the matter well you will find that the doing this requireth a much greater force then to haue the lower stone follow the vpper for it can not gape in a straight line to lett in ayre since in that position it must open at the bottome where the angle is made at the same time that it openeth at the mouth and then ayre requiring time to passe from the edges to the bottome it must in the meane while fall into the contradiction of vacuity So that if it should open to lett in ayre the stone to compasse that effect must bend in such sort as wood doth when a wedge is putt into it to cleaue it Iudge then what force it must be that should make hard marble of a great thicknesse bend like a wand and whether it would not rather breake and slide off then do so you will allow that a much lesse will raise vp the lower stone together with the vppermost It must then of necessity fall out that it will follow it if it be moued perpendicularly vpwardes And the like effect will be though it should be raysed at oblique angles so that the lowermost edge do rest all the way vpon some thing that may hinder the inferior stone from sliding aside from the vppermost And this is the very case of all those other experiments of art and nature which we haue mentioned aboue for the reason holdeth as well in water and in liquide thinges as in solide bodies vntill the weight of the liquide body ouercometh the continuity of it for then the thridde breaketh and it will ascend no higher Which height Galileo telleth vs from the workmen in the Arsenall of Venice is neere 40. foote if the water be drawne vp in a close pipe in which the aduantage of the sides helpeth the ascent But others say that the inuention is enlarged and that water may be drawne to what height one pleaseth Howsoeuer the force which nature applyeth to maintaine the continuity of quantity can haue no limitt seeing it is grounded vpon contradiction And therefore Galileo was much mistaken when he throught to make an instrument whereby to discouer the limits of this force We may then conclude that the breaking of the water must depend from the strength of other causes As for example when the grauity is so great by encreasing the bulke of the water that it will eyther ouercome the strength of the pipe or else make the sucker of the pumpe rather yield way to ayre then draw vp so great a weight for which defects if remedies be found the art may surely be enlarged without end This is particular in a syphon that when that arme of it which hangeth out of the water is lower then the superficies of the water then it will runne of it selfe after it is once sett on running by sucking The reason whereof is because the weight which is in water pendant is greater then the weight of the ascending water and thereby supplyeth
followeth that the obiect must worke vpon our sense eyther by light or att the least with light for light rebounding from the obiect round about by straight lines some part of it must needes come from the obiect to our eye Therefore by how much an obiect sendeth more light vnto our eye by so much that obiect worketh more vpon it Now seeing that diuers obiects do send light in diuers manners to our eye according to the diuers natures of those obiects in regard of hardenesse density and litlenesse of partes we must agree that such bodies do worke diuersely and do make different motions or impressiōs vpon our eye and consequētly the passion of our eye from such obiects must be diuers But there is no other diuersity of passion in the eye from the obiect in regard of seeing but that the obiect appeare diuers to vs in point of colour Therefore we must conclude that diuers bodies I meane diuers or different in that kind we here talke of must necessarily seeme to be of diuers colours meerely by the sending of light vnto our eye in diuers fashions Nay the very same obiect must appeare of different colours whensoeuer it happeneth that it reflecteth light differently to vs. As we see in cloth if it be gathered together in fouldes the bottomes of those fouldes shew to be of one kind of colour and the toppes of them or where the cloth is stretched out to the full percussion of light it appeareth to be of an other much brighter colour And accordingly painters are faine to vse almost opposite colours to expresse them In like manner if you looke vpon two pieces of the same cloth or plush whose graines lye contrawise to one an other they will likewise appeare to be of different colours Both which accidents and many others like vnto them in begetting various representations of colours do all of them arise out of lightes being more or lesse reflected from one part then from an other Thus then you see how colour is nothing else but the disposition of a bodies superficies as it is more or lesse apt to reflect light sithence the reflexion of light is made from the superficies of the seene body and the variety of its reflexion begetteth variety of colours But a superficies is more or lesse apt to reflect light according to the degrees of its being more or lesse penetrable by the force of light striking vpon it for those rayes of light that gaine no entrance into a body they are darted vpon must of necessity fly backe againe from it But if light doth gett entrance and penetrate into the body it eyther passeth quite through it or else it is swallowed vp and lost in that body The former constituteth a diaphanous body as we haue already determined And the semblance which the latter will haue in regard of colour we haue also shewed must be blacke But lett vs proceede a little further We know that two thinges render a body penetrable or easie to admitt an other body into it Holes such as we call pores and softnesse or humidity so that dryenesse hardnesse and compactednesse must be the properties which render a body impenetrable And accordingly we see that if a diaphanous body which suffereth light to runne through it be much compressed beyond what it was as when water is compressed into yce it becometh more visible that is it reflecteth more light and consequently it becometh more white for white is that which reflecteth most light On the cōtrary side softnesse vnctuousnesse and viscousnesse encreaseth blacknesse as you may experience in oyling or in greasing of wood which before was but browne for thereby it becometh more blacke by reason that the vnctuous partes added vnto the other do more easily then they single admitt into them the light that striketh vpon them and when it is gotten in it is so entangled there as though the winges of it were birdlimed ouer that it can not fly out againe And thus it is euident how the origine of all colours in bodies is plainely deduced out of the various degrees of rarity and density variously mixed and compounded Likewise out of this discourse the reason is obuious why some bodies are diaphanous and others are opacous for sithence it falleth out in the constitution of bodies that one is composed of greater partes then an other it must needes happen that light be more hindered in passing through a body composed of bigger partes then an other whose partes are lesse Neyther doth it import that the pores be supposed as great as the partes for be they neuer so large the corners of the thicke partes they belong vnto must needes breake the course of what will not bowe but goeth all in straight lines more then if the partes and pores were both lesser since for so subtile a piercer as light no pores can be too litle to giue it entrance It is true such great ones would better admitt a liquid body into them such a one as water or ayre but the reason of that is because they will bowe and take any plye to creepe into those cauities if they be large enough which light will not do Therefore it is cleare that freedome of passage can happen vnto light only there where there is an extreme great multitude of pores and partes in a very litle quantity or bulke of body which pores and partes must consequently be extreme litle ones for by reason of their multitude there must be great variety in their situation from whence it will happen that many lines must be all of pores quite through and many others all of partes although the most will be mixed of both pores and partes And so we see that although the light do passe quite through in many places yet it reflecteth from more not only in the superficies but in the very body it selfe of the diaphanous substance But in an other substāce of great partes and pores there can be but few whole lines of pores by which the light may passe from the obiect to make it be seene and consequently it must be opacous which is the contrary of Diaphanous that admitteth many rayes of light to passe through it from the obiect to the eye whereby it is seene though the Diaphanous hard body do interuene betweene them Now if we consider the generation of these two colours white and blacke in bodies we shall find that likewise to iustify and second our doctrine for white thinges are generally cold and dry and therefore are by nature ordained to be receptacles and conseruers of heat and of moysture as Physitians do note Contrariwise blacke as also greene which is neere of kinne to blacke are growing colours and are the dye of heate incorporated in aboundance of wett as we see in smoake in pittecoale in garden ground and in chymicall putrefactions all which are blacke as also in yong herbes which are generally greene as long as they are yong
sloapingnesse of the line by which the illuminant striketh one side of the glasse and cometh out at the other whem colours proceed from such a percussion To this then we must wholy apply our selues and knowing that generally when light falleth vpon a body with so great a sloaping or inclination so much of it as getteth through must needes be weake and much diffused it followeth that the reason of such colours must necessaryly consist in this diffusion and weakenesse of light which the more it is diffused the weaker it groweth and the more lines of darkenesse are betweene the lines of light and do mingle themselues with them To confirme this you may obserue how iust at the egresse from the prisme of that light which going on a litle further becometh colours no colour at all appeareth vpon a paper opposed close to the side of the glasse vntill remouing it further off the colours beginne to shew themselues vpon the edges thereby conuincing manifestly that it was the excesse of light which hindered them from appearing at the first And in like manner if you putt a burning glasse betweene the light and thâ— prisme so as to multiply the light which goeth through the prisme to the paper you destroy much of the colour by conuerting it into light But on the other side if you thicken the ayre and make it duâ—ky wiâ—h smoake or with dust you will plainely see that where the light cometh through a conuexe glasse perpendicularly opposed to the illuminant there will appeare colours on the edges of the cones that the light maketh and peraduenture the whole cones would appeare coloured if the darkening were conueniently made for if an opacous body be sett within eyther of the cones its sides will appeare coloured though the ayre be but moderately thickned which sheweth that the addition of a litle darkenesse would make that which otherwise appeareth pure light be throughly dyed into colours And thus you haue the true and adequate cause of the appearance of such colours Now to vnderstand what colours and vpon which sides will appeare we may consider that when light passeth through a glasse or other diaphanous body so much of it as shineth in the ayre or vpon some reflecting body bigger then itself after its passage through the glasse must of necessity haue darkenesse on both sides of it and so be coÌ„prised and limited by two darkenesses but if some opacous body that is lesse then the light be putt in the way of the light then it may happen contrarywise that there be darkenesse or the shadow of that opacous body betweene two lights Againe we must consider that when light falleth so vpon a prisme as to make colours the two outward rayes which proceed from the light to the two sides of the superficies at which the light entereth are so refracted that at their coming out againe through the other superficies that ray which made the lesse angle with the outward superficies of the glasse going in maketh the greater angle with the outside of the other superficies coming out and contrarywise that ray which made the greater angle going in maketh the lesser at its coming out and the two internall angles made by those two rayes and the outside of the superficies they issue at are greater then two right angles and so we see that the light dilateth it selfe at its coming out Now because rayes that issue through a superficies the neerer they are to be perpendiculars vnto that superficies so much the thicker they are it followeth that this dilatation of light at its coming out of the glasse must be made and must encrease froÌ„ that side where the angle was least at the going in and greatest at the coming out so that the neerer to the contrary side you take a part of light the thinner the light must be there and contrariwise the thicker it must be the neerer it is vnto the side where the angle at the rayes coming out is the greater Wherefore the strongest light that is the place where the light is least mixed with darkenesse must be neerer that side then the other Consequently herevnto if by an opacous body you make a shadow comprehended within this light that shadow must also haue its strongest part neerer vnto one of the lights betwixt which it is comprised then vnto the other for shadow being nothing else but the want of light hindered by some opacous body it must of necessity lye auersed from the illuminant iust as the light would haue layen if it had not beene hindered Wherefore seeing that the stronger side of light doth more impeach the darkenesse then the feebler side doth the deepest darke must incline to that side where the light is weakest that is towardes that side on which the shadow appeareth in respect of the opacous body or of the illuminant and so be a cause of deepenesse of colour on that side if it happen to be fringed with colour THE ONE AND THIRTIETH CHAPTER The causes of certaine appearances in luminous Colours with a conclusion of the discourse touching the senses and the sensible qualities OVt of these groundes we are to seeke the resolution of all such symptomes as appeare vnto vs in this kind of colours First therefore calling to mind how we haue already declared that the red colour is made by a greater proportion of light mingled with darkenesse and the blew with a lesse proportion it must follow that when light passeth through a glasse in such sort as to make colours the mixture of the light and darkenesse on that side where the light is strongest will incline to a red and their mixture on the other side where the light is weakest will make a violet or blew and this we see to fall out accordingly in the light which is tincted by going through a prisme for a red colour appeareth on that side from which the light doth dilate or decrease and a blew is on that side towardes which it decreaseth Now if a darke body be placed within this light so as to haue the light come on both sides of it we shall see the contrary happen about the borders of the picture or shadow of the darke body that is to say the red colour will be on that side of the picture which is towardes or ouer against the blew colour that is made by the glasse and the blew of the picture will be on that side which is towardes the red that is made by the glasse as you may experience if you place a slender opacous body a long the prisme in the way of the light eyther before or behind the prisme The reason whereof is that the opacous body standing in the middle enuironned by light diuideth the light and maketh two lights of that which was but one each of which lights is comprised betweene two darkenesses to witt betweene each border of shadow that ioyneth to each extreme of the light that cometh from
them duely which must be done by serious and continued reflection and not by cursary reading or by interrupted attempts yet since we haue still a whole field of proofes vntouched and that in so important a matter no euidence can be too cleare nor any paines be accounted lost that may redouble the light although it shine already bright enough to discerne what we seeke we will make vp the concert of vnanimous testimonies to this already established truth by adding those arguments we shall collect out of the manner of our soules proceeding to action vnto the others we haue drawne from our obseruations vpon her apprehensions her iudgements and her discourses Looking then into this matter the first consideration we meete withall is that our vnderstanding is in his owne nature an orderer and that his proper worke is to ranke and putt thinges in order for if we reflect vpon the workes and artes of men as a good life a common-wealth an army a house a garden all artefactes what are thâ—y but compositions of well ordered partes And in euery kind we see that he is the Master and the Architect and is a accouÌ„ted the wisest and to haue the best vnderstanding who can best or most or further then his fellowes sett thinges in order If then to this we ioyne that quantity is a thing whose nature consisteth in a capacity of hauing partes and multitude and consequently is the subiect of ordering and ranking doth it not euidently follow that our soule compared to the whole masse of bodies and to the very nature of corporeity or quantity is as a proper agent to its proper matter to worke vpon Which if it be it must necessarily be of a nobler straine and of a different and higher nature then it and consequently can not be a body or be composed of Quantity for had matter in it selfe what it expecteth and requireth from the agent it would not neede the agents helpe but of it selfe it were fitt to be an Agent Wherefore if the nature of corporeity or of body in its full latitude be to be ordered it followeth that the thing whose nature is to be an orderer must as it is such be not a body but of a superiour nature and exceeding a Body which we expresse by calling it a spirituall thing Well then if the soule be an orderer two thinges belong necessarily vnto her the one is that she haue this order within her selfe the other is that she haue power to communicate it vnto such thinges as are to be ordered The first she hath by science of which enough already hath beene said towardes proouing our intent Next that her nature is communicatiue of this order is euident out of her action and manner of working But whether of her selfe she be thus communicatiue or be so by her coniunction to the body she informeth appeareth not from thence But where experieÌ„ce falleth short reason supplyeth and sheweth vs that of her owne nature she is communicatiue of order for seeing that her action is an ordering and that in this line there are but two sortes of thinges in the world namely such as do order and such as are to be ordered it is manifest that the action must by nature and in the vniuersall consideration of it beginne from the orderer in whom order hath its life and subsistence and not from that which is to receiue it then sithence ordering is motion it followeth euidently that the soule is a moouer and a beginner of motion But since we may conceiue two sortes of moouers the one when the agent is mooued to mooue the other when of it selfe it beginneth â—he motion without being mooued we are to enquire vnto which of these two the soule belongeth But to apprehend the question rightly we will illustrate it by an example lett vs suppose that some action is fitt to beginne at tenne of the clocke now we may imagine an agent to beginne this action in two different manners the one that the clocke striking tenne breedeth or stirreth somewhat in him from whence this action followeth the other manner is that the agent may of his owne nature haue such an actuall comprehension or decurrence of time within himselfe as that without receiuing any warning from abroad but as though he moued and ordered the clocke as well as his owne instruments he may of himselfe be fitt and ready iust at that houre to beginne that action not as if the clocke told him what houre it is but as if he by gouerning the clocke made that houre to be as well as he causeth the action to beginne at that houre In the first of these manners the agent is mooued to mooue but in the second he mooueth of himselfe without being mooued by any thing else And in this second way our soule of her owne nature communicateth her selfe to quantitatiue thinges and giueth them motion which followeth out of what we haue already prooued that a soule in her owne nature is the subiect of an infinite knowledge and therefore is capable of hauing such a generall comprehension as well of time and of the course of all other thinges as of the particular action he is to doe and consequently standeth not in neede of a Monitor without her to direct her when to beginne If then it be an impreuaricable law with all bodies that none whatsoeuer can mooue vnlesse it be mooued by an other it followeth that the soule which mooueth without being stirred or excitated by any thing else is of a higher race then they and consequently is immateriall and voyde of Quantity But lett me not be mistaken in what I come from saying as though my meaning were that the soule exerciseth this way of mouing her selfe and of ordering her actions whiles she is in the body for how can she seeing she is neuer endewed with complete knowledge requisite for any action neuer fully comprehending all the circumstances of it But what I intend is that the nature of the soule considered in it selfe is such as hath a capacity and may reach to this manner of working whence I inferre that she is not a body but a spirit without determining whether she worke thus in the body or out of it that enquiry belongeth not to this place it will follow by and by But for the present hauing considered vnto what kind of working the nature of the soule in abstract is capable of attaining we will conclude this Chapter with reflecting vpon those actions of hers which fall dayly vnder our remarke as being exercised in the body In all of them we may obserue that she proceedeth with a certaine vniuersality and indifferency beyond the practise of all other creatures whatsoeuer for example if a man be spoken to or asked of a hundred seuerall thinges that he neuer thought of before in all his life he will immediately shape pertinent replyes to all that is said and returne fitting answeres to euery question as Whither such
with his vertue from an other body 4 The vertue of the loadestone is a double and not one simple vertue 5 The vettue of the loadestone worketh more strongly in the poles of it then in any other part 6 The loadestone sendeth forth its emanations spherically Which are of two kindes and each kind is strongest in that hemisphere through whose polary partes they issue out 7 Putting two loadestones within the sphere of one an other euery part of one loadestone doth not agree with euery part of the other loadestone 8 CoÌ„cerning the declination and other respects of a needle towardes the loadestone is toucheth 9 The vertue of the loadestone goeth from end to end in lines almost parallele to the axis 10 The vertue of the loadestone is not perfectly sphericall though the stone be such 11 The intention of nature in all the operations of the loadestone is to make an vnion betwixt the attractiue and attracted bodies 12 The maine globe of the earth is not a loadestone 13 The loadestone is generated in all partes or climats of the earth 14 The conformity betwixt the two motioÌ„s of magnetike thinges and of heauy thinges 1 Which is the North and which the South Pole of a loadestone 2 Whether any bodies besides magnetike ones be attractiue 3 Whether an iron placed â—erpeÌ„dicularly towardes the earth doth gett a magneticall vertue of pointing towardes the north or towardes the south in that end that lyeth downewardes 4 Why loadestones affect iron better then one an other 5 Gilberts reason refuted touching a capped loadestone that taketh vp more iron then one not capped and an iron impregnated that in some case draweth more strongly then the stone it selfe 6 Galileus his opinion touching the former effects refuted 7 The Authors solution to the former questions 8 The reasoÌ„ why in the former case a lesser loadestone doth draw the interiacent iroÌ„ froÌ„ the greater 9 Why the variation of a touched needle froÌ„ the north is greater the neerer you go to the Pole 10 Whether in the same part of the world a touched needle may att one time vary more froÌ„ the north and att an other time lesse 11 The whole doctrine of the loadestone summed vp in short 1 The connexion of the following Chapters with the precedent ones 2 Concerning seuerall coÌ„positions of mixed bodies 3 Two sortes of liuing creatures 4 An engine to expresse the first sort of liuing creatures 5 An other engine by which may be expressed the second sort of liuing creatures 6 The two former engines and some other comparisons applyed to expresse the two seuerall sortes of liuing creatures 7 How plantes are framed 8 How sensitiue creatures are formed 1 The opinion that the seede containeth formally euery part of the parent 2 The former opinion reiected 3 The Authors opinion of this question 4 Their opinion refuted who hold that euery thing containeth formally all thinges 5 The Authors opinion concerning the generation of Animals declared and confirmed 6 That one substance is changed into an other 7 Concerning the hatching of chickens and the generation of other Animals 8 From whence it happeneth that the deficiences or excrescences of the parents body are often seene in their children 9 The difference between the Authors opinion and the former one 10 That the hart is imbued with the generall specifike vertues of the whole body whereby is confirmed the doctrine of the two former paragraphes 11 That the hart is the first part generated in a liuing creature 1 That the figure of an Animal is produced by ordinarie secoÌ„â— causes as well as any other corporeall effect 2 That the seuerall figures of bodies proceed from a defect in one of the three dimensions caused by the concurraÌ„ce of accidentall causes 3 The former doctrine is confirmed by seuerall instances 4 The same doctrine applyed to Plants 5 The same doctrine declared in leafes of trees 6 The same applyed to the bodies of Animals 7 In what sense the Author doth admitt of Vis formatrix 1 Fromwhence doth proceed the primary motion and growth in Plantes 2 Monsieur des Cartes his opinion touching the motion of the hart 3 The former opinion reiected 4 The Authors opinion concerning the motion of the hart 5 The motion of the hart dependeth originally of its fibers irrigated by bloud 6 An obiection answered against the former doctrine 7 The circulatioÌ„ of the bloud and other effects that follow the motion of the hart 8 Of Nutrition 9 Of Augmentation 10 Of death and sicknesse 1 The coÌ„nexion of the subsequent chapters with the precedent 2 Of the senses and sensible qualities in generall And of the end for which they serue 3 Of the sense of touching and that both it and its qualities are bodies 4 Of the tast and its qualities that they are bodies 5 That the smell and its qualities are reall bodies 6 Of the conformity betwixt the two senses of smelling and tasting 7 The reasoÌ„ why the sense of smelling is not so perfect in man as in beastes with a wonderfull historie of a man who could wind a sent as well aâ— any beast 1 Of the sense of hearing and that sound is purely motioÌ„ 2 Of diuers artes belonging to the sense of hearing all which confirme that sound is nothing but motion 3 The same is confirmed by the effects caused by great noises 4 That solide bodies may conueye the motion of the ayre or sound to the organe of hearing 5 Where the motion is interrupted there is no sound 6 That not only the motion of the ayre but all other motions coming to our eares make sounds 7 How one sense may supply the want of an other 8 Of one who could discerne souÌ„ds of words with his eyes 9 Diuers reasons to proue sound to be nothing els but a motioÌ„ of some reall body 1 That Colours are nothing but light mingled with darknesse or the disposition off a bodies superficies apt to reflect light so mingled 2 CoÌ„cerning the disposition of those bodies which produce white or blacke coulours 3 The former doctrine coÌ„firmed by Aristotâ—les authority reason and experience 4 How the diuersity of coulours doe follow out of various degrees of rarity and density 5 Why some bodies are Diaphanous others opacous 6 The former doctrine of coulours coÌ„firmed by the generation of white and Blacke in bodies 1 Apparitions of coulours through a prisme or triaÌ„gular glasse are of two sortes 2 The seuerall parts of the obiect make seuerall angles at their entrance into the prisme 3 The reason why some times the same obiect appeareth throwgh the prisme in two places and in one place more liuely in the other place more dimmes 4 The reason of the various colours that appeare in looking throwgh a prisme 5 The reasonÌ„ why the prisme in one position may make the colours appeare quite contrary to what