[A ruler is merely] the trustee of the rights of other men and he must always stand in dread of having in some way violated these rights.

Melancholy characterizes those with a superb sense of the sublime.

Dare to know! Have the courage to use your own intelligence!

In every department of physical science there is only so much science, properly so-called, as there is mathematics.

Enlightenment is man's emergence from his self-imposed nonage. Nonage is the inability to use one's own understanding without another's guidance. This nonage is self-imposed if its cause lies not in lack of understanding but in indecision and lack of courage to use one's own mind without another's guidance. Dare to know!

Philosophy stands in need of a science which shall determine the possibility, principles, and extent of human knowledge à priori.

God, freedom, and immortality are untenable in the light of pure reason.