The Fifth Part.

of Compound bodies. And for this Rejection of a Vulgar Error, they ought not to be deny’d what praise men may deserve for exploding a Doctrine whose Imperfections are so conspicuous, that men needed but not to shut their Eyes, to discover them. But I am mistaken, if our Hermetical Philosophers Themselves need not, as well as the Peripateticks, have Recourse to more Fruitfull and Comprehensive Principles then the tria Prima, to make out the Properties of the Bodies they converse with. Not to accumulate Examples to this purpose, (because I hope for a fitter opportunity to prosecute this Subject) let us at present only point at Colour, that you may guess by what they say of so obvious and familiar a Quality, how little Instruction we are to expect from the Tria Prima in those more abstruse ones, which they with the Aristotelians stile Occult. For about Colours, neither do they at all agree among themselves, nor have I met with any one, of which of the three Perswasions soever, that does intelligibly explicate Them. The Vulgar Chymists are wont to ascribe Colours to Mercury; Paracelsus in divers places attributes them to Salt; and Sennertus,De Cons. & dissen. cap. 11. pag. 186. having recited their differing Opinions, Dissents from both, and referrs Colours rather unto Sulphur. But how Colours do, nay, how they may, arise from either of these Principles, I think you will scarce say that any has yet intelligibly explicated. And if Mr. Boyle will allow me to shew you the Experiments which he has collected about Colours, you will, I doubt not, confess that bodies exhibite colours, not upon the Account of the Predominancy of this or that Principle in them, but upon that of their Texture, and especially the Disposition of their superficial parts, whereby the Light rebounding thence to the Eye is so modifi’d, as by differing Impressions variously to affect the Organs of Sight. I might here take notice of the pleasing variety of Colours exhibited by the Triangular glass, (as ’tis wont to be call’d) and demand, what addition or decrement of either Salt, Sulphur, or Mercury, befalls the Body of the Glass by being Prismatically figur’d; and yet ’tis known, that without that shape it would not affor’d those colours as it does. But because it may