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.

Act in such a way that you will be worthy of being happy.

Immaturity is the incapacity to use one's intelligence without the guidance of another.

No state at war with another state should engage in hostilities of such a kind as to render mutual confidence impossible when peace will have been made.

I had therefore to remove knowledge, in order to make room for belief.

What are the aims which are at the same time duties? They are perfecting of ourselves, the happiness of others.

If an offender has committed murder, he must die. In this case, no possible substitute can satisfy justice. For there is no parallel between death and even the most miserable life, so that there is no equality of crime and retribution unless the perpetrator is judicially put to death.