If man makes himself a worm he must not complain when he is trodden on.

The greatest human quest is to know what one must do in order to become a human being.

The wise man can change his mind; the stubborn one, never.

Always regard every man as an end in himself, and never use him merely as a means to your ends [i.e., respect that each person has a life and purpose that is their own; do not treat people as objects to be exploited].

Happiness is not an ideal of reason, but of imagination.

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.

Fallacious and misleading arguments are most easily detected if set out in correct syllogistic form.