The Sceptical Chymist: or Chymico-Physical Doubts & Paradoxes, Touching the Spagyrist's Principles Commonly call'd Hypostatical; As they are wont to be Propos'd and Defended by the Generality of Alchymists. Whereunto is præmis'd Part of another Discourse relating to the same Subject.

How it begins

I Perceive that divers of my Friends have thought it very strange to hear me speak so irresolvedly, as I have been wont to do, concerning those things which some take to be the Elements, and others to be the Principles of all mixt Bodies. But I blush not to acknowledge that I much lesse scruple to confess that I Doubt, when I do so, then to profess that I Know what I do not: And I should have much stronger Expectations then I dare yet entertain, to see Philosophy solidly establish’t, if men would more carefully distinguish those things that they know, from those that they ignore or do but think, and then explicate clearly the things they conceive they understand, acknowledge ingenuously what…