In law a man is guilty when he violates the rights of others. In ethics he is guilty if he only thinks of doing so.

By a lie a man throws away and, as it were, annihilates his dignity as a man. A man who himself does not believe what he tells another ... has even less worth than if he were a mere thing. ... makes himself a mere deceptive appearance of man, not man himself.

It is not God's will merely that we should be happy, but that we should make ourselves happy

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

Even philosophers will praise war as ennobling mankind, forgetting the Greek who said: 'War is bad in that it begets more evil than it kills.'

The question is not so much whether there is life on Mars as whether it will continue to be possible to live on Earth

When a thoughtful human being has overcome incentives to vice and is aware of having done his bitter duty, he finds himself in a state that could be called happiness, a state of contentment and peace of mind in which virtue is its own reward.