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18. Of the blackness of a Charcoal, and of Light.
I Cannot in reason give my consent to those Dioptri∣cal Writers, who conceive that the blackness of a Charcoal proceeds from the Porousness of its parts, and the absence of light, viz. that light, not being reflected in the Pores of a Charcoal, doth make it obscure, and consequently appear black; for the opinion which holds that all Colours are caused by the various reflexi∣on of Light, has but a weak and uncertain Ground, by reason the refraction or reflection of light is so in∣constant, as it varies and alters continually; and there being so many reflexions and positions of Light, if they were the true cause of Colours, no Colour would ap∣pear constantly the same, but change variously, ac∣cording to the various reflexion of Light; whereas, on the contrary, we see that natural and inherent Colours continue always the same, let the position and reflection of Light be as it will; besides, there being different co∣loured Creatures, if all had the same position and re∣flexion of light, they would not appear of divers, but all of one colour, the contrary whereof is proved by experience. I will not say, but the refraction and va∣rious position of light may vary and alter a natural and inherent colour exteriously so, as to cause, for exam∣ple, a natural blew to appear green, or a natural green to appear red, &c. but those figures which