difficult to be sure, that that which they alwayes differ from is the true. And our Carneades by holding the Negative, he has this Advantage, that if among all the Instances he brings to invalidate all the Vulgar Doctrine of those he Disputes with, any one be Irrefragable, that alone is sufficient to overthrow a Doctrine which Universally asserts what he opposes. For, it cannot be true, that all Bodies whatsoever that are reckon’d among the Perfectly mixt Ones, are Compounded of such a Determinate Number of such or such Ingredients, in case any one such Body can be produc’d, that is not so compounded; and he hopes too, that Accurateness will be the less expected from him, because his undertaking obliges him to maintain such Opinions in Chymistry, and that chiefly by Chymical Arguments, as are Contrary to the very Principles of the Chymists; From whose writings it is not Therefore like he should receive any intentionall Assistance, except from some Passages of the Bold and Ingenious Helmont, with whom he yet disagrees in many things (which reduce him to explicate Divers Chymical Phænomena, according to other Notions;) And of whose Ratiocinations, not only some seem very Extravagant, but even the Rest are not wont to be as considerable as his Experiments. And though it be True indeed, that some Aristotelians have occasionally written against the Chymical Doctrine he Oppugnes, yet since they have done it according to their Principles, And since our Carneades must as well oppose their Hypothesis as that of the Spagyrist, he was fain to fight his Adversaries with their own Weapons, Those of the Peripatetick being Improper, if not hurtfull for a Person of his Tenents; besides that those Aristotelians, (at Least, those he met with,) that have written against the Chymists, seem to have had so little Experimental Knowledge in Chymical Matters, that by their frequent Mistakes and unskilfull Way of Oppugning, they have too often expos’d Themselves to the Derision of their Adversaries, for writing so Confidently against what they appear so little to understand.

And Lastly, Carneades hopes, he shall doe the Ingenious this Piece of service, that by having Thus drawn the Chymists Doctrine out of their Dark and Smoakie Laboratories, and both brought it into the open light, and shewn the weakness of their Proofs, that have hitherto been wont to be brought for it, either Judicious Men shall henceforth be allowed calmly and after due information to disbelieve it, or those abler Chymists, that are zealous for the reputation of it, will be oblig’d to speak plainer then hitherto has been done, and maintain it by better Experiments and Arguments then Those Carneades hath examin’d: so That he hopes, the Curious will one Way or other Derive either satisfaction or instruction from his endeavours. And as he is ready to make good the profession he makes in the close of his Discourse, he being ready to be better inform’d, so he expects either to be indeed inform’d, or to be let alone. For Though if any Truly knowing Chymists shall Think fit in a civil and rational way to shew him any truth touching the matter in Dispute That he yet discernes not, Carneades will not refuse either to admit, or to own a Conviction: yet if any impertinent Person shall, either to get Himself a Name, or for what other end soever, wilfully or carelesly mistake the State of the Controversie, or the sence of his Arguments, or shall rail instead of arguing, as hath been done of Late in Print by divers Chymists;G. and F. and H. and others, in their books against one another. or lastly, shall write against them in a canting way; I mean, shall express himself in ambiguous or obscure termes, or argue from experiments not intelligibly enough Deliver’d, Carneades professes, That he values his time so much, as not to think the answering such Trifles worth the loss of it.

And now having said thus much for Carneades, I hope the Reader will give me leave to say something too for my self.

And first, if some morose Readers shall find fault with my having made the Interlocutors upon occasion complement with one another, and that I have almost all along written these Dialogues in a stile more Fashionable then That of meer scholars is wont to be, I hope I shall be excus’d by them that shall consider, that to keep a due decorum in the Discourses, it was fit that in a book written by a Gentleman, and wherein only Gentlemen are introduc’d as speakers, the Language should be more smooth, and the Expressions more civil than is usual in the more Scholastick way of writing. And indeed, I am not sorry to have this Opportunity of giving an example how to manage even Disputes with Civility; whence perhaps some Readers will be assisted to discern a Difference betwixt Bluntness of speech and Strength of reason, and find that a man may be a Champion for Truth, without being an Enemy to Civility; and may confute an Opinion without railing at Them that hold it; To whom he that desires to convince and not to provoke them, must make some amends by his Civility to their Persons, for his severity to their mistakes; and must say as little else as he can, to displease them, when he says that they are in an error.

But perhaps other Readers will be less apt to find fault with the Civility of my Disputants, than the Chymists will be, upon the reading of some Passages of the following Dialogue, to accuse Carneades of Asperity. But if I have made my Sceptick sometimes speak sleightingly of the Opinions he opposes, I hope it will not be found that I have done any more, than became the Part he was to act of an Opponent: Especially, if what I have made him say be compar’d with what the Prince of the Romane Orators himself makes both great Persons and Friends say of one anothers Opinions, in his excellent Dialogues, De Natura Deorum: And I shall scarce be suspected of Partiality, in the case, by them that take Notice that there is full as much (if not far more) liberty of sleighting their Adversaries Tenents to be met with in the Discourses of those with whom Carneades disputes. Nor needed I make the Interlocutors speak otherwise then freely in a Dialogue, wherein it was sufficiently intimated, that I meant not to declare my own Opinion of the Arguments propos’d, much lesse of the whole Controversy it self otherwise than as it may by an attentive Reader be guess’d at by some Passages of Carneades: (I say, some Passages, because I make not all that he says, especially in the heat of Disputation, mine,) partly in this Discourse, and partly in some other Dialogues betwixt the same speakers (though they treat not immediately of the Elements) which have long layn by me, and expect the Entertainment that these present Discourses will meet with. And indeed they will much mistake me, that shall conclude from what I now publish, that I am at Defyance with Chymistry, or would make my Readers so. I hope the Specimina I have lately publish’d of an attempt to shew the usefulness of Chymical Experiments to Contemplative Philosophers, will give those that shall read them other thoughts of me: & I had a design (but wanted opportunity) to publish with these Papers an Essay I have lying by me, the greater part of which is Apologetical for one sort of Chymists. And at least, as for those that know me, I hope the pain I have taken in the fire will both convince them, that I am far from being an Enemy to the Chymists Art, (though I am no friend to many that disgrace it by professing it,) and perswade them to believe me when I declare that I distinguish betwixt those Chymists that are either Cheats, or but Laborants, and the true Adepti; By whom, could I enjoy their Conversation, I would both willingly and thankfully be instructed; especially concerning the Nature and Generation of Metals: And possibly, those that know how little I have remitted of my former addictedness to make Chymical Experiments,