A categorical imperative would be one which represented an action as objectively necessary in itself, without reference to any other purpose.

. . . as to moral feeling, this supposed special sense, the appeal to it is indeed superficial when those who cannot think believe that feeling will help them out, even in what concerns general laws: and besides, feelings which naturally differ infinitely in degree cannot furnish a uniform standard of good and evil, nor has any one a right to form judgments for others by his own feelings. . . .

A science of all these possible kinds of space [the higher dimensional ones] would undoubtedly be the highest enterprise which a finite understanding could undertake in the field of geometry... If it is possible that there could be regions with other dimensions, it is very likely that God has somewhere brought them into being.

Out of the crooked timber of humanity, no straight thing was ever made.

It is by his activities and not by enjoyment that man feels he is alive. In idleness we not only feel that life is fleeting, but we also feel lifeless.

There is nothing higher than reason.

Maturity is having the courage to use one's own intelligence!