Educating the mind without educating the heart is no education at all.

The greatness of a nation and its moral progress can be judged by the way its animals are treated.

Man prays for mercy, but is unwilling to extend it to others. 

What do they know-all these scholars, all these philosophers, all the leaders of the world - about such as you? They have convinced themselves that man, the worst transgressor of all the species, is the crown of creation. All other creatures were created merely to provide him with food, pelts, to be tormented, exterminated. 

One cannot step twice in the same river.

Entities should not be multiplied unnecessarily.

To be is to be perceived.

If a tree falls in the forest and no one is there to hear it, does it make a sound?

We live in the best of all possible worlds.

Never let your sense of morals prevent you from doing what is right.