It may be objected, These oppositions might be profitable, as well to make me know my faults, as if any thing of mine were good to make others by that means come to a better understanding thereof; and as many may see more then one man, beginning from this time to make use of my grounds, they might also help me with their invention. But although I know my self extremely subject to fail, and do never almost trust my first thoughts; yet the experience I have of the objections which may be made unto me, hinder me from hoping for any profit from them; For I have often tried the judgments as well of those whom I esteem'd my friends, as of others whom I thought indifferent, and even also of some, whose malignity and envie did sufficiently discover what the affection of my friends might hide. But it seldom happened that any thing was objected against me, which I had not altogether foreseen, unless it were very remote from my Subject: So that I never almost met with any Censurer of my opinions, that seemed unto me either less rigorous, or less equitable then my self. Neither did I ever observe, that by the disputations practiced in the Schools any Truth which was formerly unknown, was ever discovered. For whilest every one seeks to overcome, men strive more to maintain probabilities, then to weigh the reasons on both sides; and those who for a long time have been good Advocates, are not therefore the better Judges afterwards. As for the benefit which others may receive from the communication of my thoughts, it cannot also be very great, forasmuch as I have not yet perfected them, but that it is necessary to add many things thereunto, before a usefull application can be made of them. And I think I may say without vanity, That if there be any one capable thereof, it must be my self, rather then any other. Not but that there may be divers wits in the world incomparably better then mine; but because men cannot so well conceive a thing and make it their own, when they learn it of another, as when they invent it themselves: which is so true in this Subject, that although I have often explain'd some of my opinions to very understanding men, and who, whilest I spake to them, seem'd very distinctly to conceive them; yet when they repeated them, I observ'd, that they chang'd them almost always in such a manner, that I could no longer own them for mine. Upon which occasion, I shall gladly here desire those who come after me, never to beleeve those things which may be delivered to them for mine, when I have not published them my self. And I do not at all wonder at the extravagancies which are attributed to all those ancient Philosophers, whose Writings we have not; neither do I thereby judge, that their thoughts were very irrationall, seeing they were the best Wits of their time; but onely that they have been ill convey'd to us: as it appears also, that never any of their followers surpass'd them. And I assure my self, that the most passionate of those,