As I for my part am perswaded, that had I been taught from my youth all the Truths whose demonstrations I have discovered since, and had taken no pains to learn them, perhaps I should never have known any other, or at least, I should never have acquired that habit, and that faculty which I think I have, still to finde out new ones, as I apply my self to the search of them. And in a word, if there be in the world any work which cannot be so well ended by any other, as by the same who began it, it's that which I am now about. It's true, That one man will not be sufficient to make all the experiments which may conduce thereunto: But withall, he cannot profitably imploy other hands then his own, unlesse it be those of Artists, or others whom he hires, and whom the hope of profit (which is a very powerfull motive) might cause exactly to do all those things he should appoint them: For as for voluntary persons, who by curiosity or a desire to learn, would perhaps offer themselves to his help, besides that commonly they promise more then they perform, and make onely fair propositions, whereof none ever succeeds, they would infallibly be paid by the solution of some difficulties, or at least by complements and unprofitable entertainments, which could not cost him so little of his time, but he would be a loser thereby. And for the Experiments which others have already made, although they would even communicate them to him (which those who call them Secrets would never do,) they are for the most part composed of so many circumstances, or superfluous ingredients, that it would be very hard for him to decypher the truth of them: Besides, he would find them all so ill exprest, or else so false, by reason that those who made them have laboured to make them appear conformable to their principles; that if there were any which served their turn, they could not at least be worth the while which must be imployed in the choice of them. So that, if there were any in the world that were certainly known to be capable of finding out the greatest things, and the most profitable for the Publick which could be, and that other men would therefore labour alwayes to assist him to accomplish his Designes; I do not conceive that they could do more for him, then furnish the expence of the experiments whereof he stood in need; and besides, take care only that he may not be by any body hindred of his time. But besides that, I do not presume so much of my Self, as to promise any thing extraordinary, neither do I feed my self with such vain hopes, as to imagine that the Publick should much interesse it self in my designes; I have not so base a minde, as to accept of any favour whatsoever, which might be thought I had not deserved.