2 But Pyrophilus, I muſt not at preſent any further proſecute the Conſideration of the importance of Experiments about Colours, not only becauſe you will in the following papers finde ſome inſtances, that would here
be preſented you out of their due place, of the uſe that may be made of ſuch Experiments, in diſcovering in divers bodies, what kind the ſalt is, that is predominant in them; but alſo becauſe a ſpeculative Naturaliſt might juſtly enough allege, that as Light is ſo pleaſing an object, as to be well worth our looking on, though it diſcover'd to us nothing but its ſelf; ſo modifi'd Light called Colour, were worth our contemplation, though by underſtanding its Nature we ſhould be taught nothing elſe. And however, I need not make either you or my ſelf excuſes for entertaining you on the ſubject I am now about to treat of, ſince the pleaſure Pyro: takes in mixing and laying on of Colours, will I preſume keep him, and will (I am ſure) keep mee from thinking it troubleſome to ſet down, eſpecially after the tedious proceſſes (about other matters) wherewith I fear I may have tyr'd him, ſome eaſie, and not unpleaſant Experiments relating to that ſubject.
3 But, before we deſcend to the more particular conſiderations, we are to preſent you concerning Colours, I preſume it will be ſeaſonable to propoſe at the very entrance a Diſtinction; the ignorance or neglect of which, ſeems to mee to have frequently enough occaſioned either miſtakes or confuſion
in the Writings of divers Modern Philoſophers; for Colour may be conſidered, either as it is a quality reſiding in the body that is ſaid to be coloured, or to modifie the light after ſuch or ſuch a manner; or elſe as the Light it ſelf, which ſo modifi'd, ſtrikes upon the organ of ſight, and ſo cauſes that Senſation which we call Colour; and that this latter may be look'd upon as the more proper, though not the uſual acception of the word Colour, will be made probable by divers paſſages in the inſuing part of our diſcourſe; and indeed it is the Light it ſelf, which after a certain manner, either mingled with ſhades, or ſome other waies troubled, ſtrikes our eyes, that does more immediately produce that motion in the organ, upon whoſe account men ſay they ſee ſuch or ſuch a Colour in the object; yet, becauſe there is in the body that is ſaid to be coloured, a certain diſpoſition of the ſuperficial particles, whereby it ſends the Light reflected, or refracted, to our eyes thus and thus alter'd, and not otherwiſe, it may alſo in ſome ſenſe be ſaid, that Colour depends upon the viſible body; and therefore we ſhall not be againſt that way of ſpeaking of Colours that is moſt uſed among the Modern Naturaliſts, provided we be allowed to have recourſe when occaſion ſhall
require to the premis'd diſtinction, and to take the more immediate cauſe of Colour to be the modifi'd Light it ſelf, as it affects the Senſory; though the diſpoſition alſo of the colour'd body, as that modifies the Light, may be call'd by that name Metonimically (to borrow a School term) or Efficiently, that is in regard of its turning the Light, that rebounds from it, or paſſes thorow it, into this or that particular Colour.
4 I know not whether I may not on this occaſion add, that Colour is ſo far from being an Inherent quality of the object in the ſenſe that is wont to be declar'd by the Schools, or even in the ſenſe of ſome Modern Atomiſts, that, if we conſider the matter more attentively, we ſhall ſee cauſe to ſuſpect, if not to conclude, that though Light do more immediately affect the organ of ſight, than do the bodies that ſend it thither, yet Light it ſelf produces the ſenſation of a Colour, but as it produces ſuch a determinate kind of local motion in ſome part of the brain; which, though it happen moſt commonly from the motion whereinto the ſlender ſtrings of the Retina are put, by the appulſe of Light, yet if the like motion happen to be produc'd by any other cauſe, wherein the Light concurrs not at
all, a man ſhall think he ſees the ſame Colour. For proof of this, I might put you in mind, that 'tis uſual for dreaming men to think they ſee the Images that appear to them in their ſleep, adorn'd ſome with this, and ſome with that lively Colour, whilſt yet, both the curtains of their bed, and thoſe of their eyes are cloſe drawn. And I might add the confidence with which diſtracted perſons do oftentimes, when they are awake, think, they ſee black fiends in places, where there is no black object in ſight without them. But I will rather obſerve, that not only when a man receives a great ſtroak upon his eye, or a very great one upon ſome other part of his head, he is wont to ſee, as it were, flaſhes of lightning, and little vivid, but vaniſhing flames, though perhaps his eyes be ſhut: But the like apparitions may happen, when the motion proceeds not from ſomething without, but from ſomething within the body, provided the unwonted fumes that wander up and down in the head, or the propagated concuſſion of any internal part in the body, do cauſe about the inward extremities of the Optick Nerve, ſuch a motion as is wont to be there produc'd, when the ſtroak of the Light upon the Retina makes us conclude, that we ſee either Light, or ſuch and ſuch a
Colour: This the moſt ingenious Des Cartes hath very well obſerv'd, but becauſe he ſeems not to have exemplifi'd it by any unobvious or peculiar obſervation, I ſhall indeavour to illuſtrate this doctrine by a few Inſtances.
5 And firſt, I remember, that having, through Gods goodneſs, been free for ſeveral years, from troubleſome Coughs, being afterwards, by an accident, ſuddenly caſt into a violent one, I did often, when I was awaked in the night by my diſtempers, obſerve, that upon coughing ſtrongly, it would ſeem to mee, that I ſaw very vivid, but immediately diſappearing flames, which I took particular notice of, becauſe of the conjecture I am now mentioning.
6 An excellent and very diſcreet perſon, very near ally'd both to you and mee, was relating to mee, that ſome time ſince, whilſt ſhe was talking with ſome other Ladies, upon a ſudden, all the objects, ſhe looked upon, appeared to her dyed with unuſual Colours, ſome of one kind, and ſome of another, but all ſo bright and vivid, that ſhe ſhould have been as much delighted, as ſurpriz'd with them, but that finding the apparition to continue, ſhe fear'd it portended ſome very great alteration as to her health: As indeed the day after ſhe was aſſaulted