"Dare to know! (Sapere aude.) 'Have courage to use your own understanding!'—that is the motto of enlightenment."

"If justice perishes, then it is no longer worthwhile for men to live on earth."

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

"We can know only appearances, not things in themselves."

"The Negroes and Americans will hence never be capable of founding an orderly civil society for themselves."