All our knowledge begins with the senses...

A society that is not willing to demand a life of somebody who has taken somebody else’s life is simply immoral.

It is difficult for the isolated individual to work himself out of the immaturity which has become almost natural for him.

A lie is the abandonment and, as it were, the annihilation of the dignity by man.

Natural science physics contains in itself synthetical judgments a priori, as principles. ... Space then is a necessary representation a priori, which serves for the foundation of all external intuitions.

Enlightenment is the liberation of man from his self-caused state of minority... Supere aude! Dare to use your own understanding!is thus the motto of the Enlightenment.

Reason must approach nature in order to be taught by it. It must not, however, do so in the character of a pupil who listens to everything that the teacher chooses to say, but of an appointed judge who compels the witness to answer questions which he has himself formulated.