on our Eyes from the very Boſom of thoſe Pores; that the ſmaller the Pores of a Body are, the more ſuch a Body is tranſparent. Thus Paper which reflects the Light when dry, tranſmits it when oil'd, becauſe the Oil, by filling its Pores, makes them much ſmaller.
'Tis there that examining the vaſt Poroſity of Bodies, every Particle having its Pores, and every Particle of thoſe Particles having its own; he ſhows we are not certain that there is a cubic Inch of ſolid Matter in the Univerſe, ſo far are we from conceiving what Matter is. Having thus divided, as it were. Light into its Elements, and carried the Sagacity of his Diſcoveries ſo far, as to prove the Method of diſtinguiſhing compound Colours from ſuch as are primitive; he ſhews, that theſe elementary Rays ſeparated by the Priſm, are rang'd in their Order for no other Reaſon but becauſe they are refracted in that very Order; and 'tis this Property (unknown till he diſcover'd it) of breaking or ſplitting in this Proportion; 'tis this unequal Refraction of
