The Universe is a friendly place.

Life is a preparation for the future; and the best preparation for the future is to live as if there were none.

Those instrumental goods which should serve to maintain the life and health of all human beings should be produced by the least possible labour of all.

Relativity applies to physics, not ethics.

I live in that solitude which is painful in youth, but delicious in the years of maturity.

The greater the doubt, the greater the awakening

I do not believe that a man should be restrained in his daily actions by being afraid of punishment after death or that he should do things only because in this way he will be rewarded after he dies. This does not make sense. The proper guidance during the life of a man should be the weight that he puts upon ethics and the amount of consideration that he has for others.