We can judge the heart of a man by his treatment of animals.

Two things strike me dumb: the infinite starry heavens, and the sense of right and wrong in man.

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.

Notion without intuition is empty, intuition without notion is blind.

The light dove, in free flight cutting through the air the resistance of which it feels, could get the idea that it could do even better in airless space. Likewise, Plato abandoned the world of the senses because it posed so many hindrances for the understanding, and dared to go beyond it on the wings of the ideas, in the empty space of pure understanding.

We are not rich by what we possess but by what we can do without.

Heaven has given human beings three things to balance the odds of life: hope, sleep, and laughter.