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).

Reason can never prove the existence of God.

The hand is the visible part of the brain.

How then is perfection to be sought? Wherein lies our hope? In education, and in nothing else.

Act in such a way that you treat humanity, whether in your own person or in the person of any other, never merely as a means to an end, but always at the same time as an end.

Human reason has the peculiar fate in one species of its cognitions that it is burdened with questions which it cannot dismiss, since they are given to it as problems by the nature of reason itself, but which it also cannot answer, since they transcend every capacity of human reason.

Two things strike me dumb: the infinite starry heavens, and the sense of right and wrong in man.