But I consider further, that Chymists are (for ought I have found) far from being able to explicate by any of the _Tria Prima_, those qualities which they pretend to belong primarily unto it, and in mixt Bodies to Deduce from it. Tis true indeed, that such qualities are not explicable by the four Elements; but it will not therefore follow, that they are so by the three hermetical Principles; and this is it that seems to have deceiv'd the Chymists, and is indeed a very common mistake amongst most Disputants, who argue as if there could be but two Opinions concerning the Difficulty about which they contend; and consequently they inferr, that if their Adversaries Opinion be Erroneous, Their's must needs be the Truth; whereas many questions, and especially in matters Physiological, may admit of so many Differing _Hypotheses_, that 'twill be very inconsiderate and fallacious to conclude (except where the Opinions are precisely Contradictory) the Truth of one from the falsity of another. And in our particular case 'tis no way necessary, that the Properties of mixt Bodies must be explicable either by the Hermetical, or the _Aristotelian Hypothesis_, there being divers other and more plausible wayes of explaining them, and especially that, which deduces qualities from the motion, figure, and contrivance of the small parts of Bodies; as I think might be shewn, if the attempt were as seasonable, as I fear it would be Tedious. I will allow then, that the Chymists do not causelessly accuse the Doctrine of the four elements of incompetency to explain the Properties 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_,[25] 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