[W]hat alone has value is the use to which life is put and the end to which it is directed. The value of life has to be created by man, it cannot be … - Immanuel Kant

There is something splendid about innocence; but what is bad about it, in turn, is that it cannot protect itself very well and is easily seduced.

The guidelines for achieving wisdom consist of three leading maxims: 1) Think for yourself; 2) (in communication with other people) Put yourself in the place of the other person; 3) Always think by remaining faithful to your own self.

I have in this treatise followed the mathematical method, if not with all strictness, at least imitatively, not in order, by a display of profundity, to procure a better reception for it, but because I believe such a system to be quite capable of it, and that perfection may in time be obtained by a cleverer hand, if stimulated by this sketch, mathematical investigators of nature should find it not unimportant to treat the metaphysical portion, which anyway cannot be got rid of, as a special fundamental department of general physics, and to bring it into unison with the mathematical doctrine of motion.