Time is not an empirical concept. For neither co-existence nor succession would be perceived by us, if the representation of time did not exist as a foundation a priori.

It is not necessary that whilst I live I live happily; but it is necessary that so long as I live I should live honourably.

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

Look closely. The beautiful may be small.

Freedom can never be comprehended, nor even can insight into it be gained.

Our knowledge springs from two fundamental sources of the mind; the first is the capacity of receiving representations (receptivity for impressions), the second is the power of knowing an object through these representations (spontaneity [in the production] of concepts).

. . . 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. . . .