And I thought it easie for me to choose some matters, which being not subject to many Controversies, nor obliging me to declare any more of my Principles then I would willingly, would neverthelesse expresse clearly enough, what my abilities or defects are in the Sciences. Wherein I cannot say whether I have succeeded or no; neither will I prevent the judgment of any man by speaking of my own Writings: but I should be glad they might be examin'd; and to that end I beseech all those who have any objections to make, to take the pains to send them to my Stationer, that I being advertised by him, may endeavour at the same time to adjoyn my Answer thereunto: and by that means, the Reader seeing both the one and the other, may the more easily judge of the Truth. For I promise, that I will never make any long Answers, but only very freely confesse my own faults, if I find them; or if I cannot discover them, plainly say what I shal think requisite in defence of what I have writ, without adding the explanation of any new matter, that I may not endlesly engage my self out of one into another. Now if there be any whereof I have spoken in the beginning, of the Opticks and of the Meteors, which at first jarr, by reason that I call them Suppositions, and that I seem not willing to prove them; let a man have but the patience to read the whole attentively, and I hope he will rest satisfied: For (me thinks) the reasons follow each other so closely, that as the later are demonstrated by the former, which are their Causes; the former are reciprocally proved by the later, which are their Effects. And no man can imagine that I herein commit the fault which the Logicians call a _Circle_; for experience rendring the greatest part of these effects most certain, the causes whence I deduce them serve not so much to prove, as to explain them; but on the contrary, they are those which are proved by them. Neither named I them Suppositions, that it might be known that I conceive my self able to deduce them from those first Truths which I have before discovered: But that I would not expresly do it to crosse certain spirits, who imagine that they know in a day al what another may have thought in twenty yeers, as soon as he hath told them but two or three words; and who are so much the more subject to erre, and less capable of the Truth, (as they are more quick and penetrating) from taking occasion of erecting some extravagant Philosophy on what they may beleeve to be my Principles, and lest the fault should be attributed to me. For as for those opinions which are wholly mine, I excuse them not as being new, because that if the reasons of them be seriously considered, I assure my self, they will be found so plain, and so agreeable to common sense, that they will seem less extraordinary and strange then any other which may be held on the same Subjects. Neither do I boast that I am the first Inventor of any of them; but of this indeed, that I never admitted any