One of the worst forms of mental suffering is boredom, not knowing what to do with oneself and one's life. Even if man had no monetary, or any other reward, he would be eager to spend his energy in some meaningful way because he could not stand the boredom which inactivity produces.

Man always dies before he is fully born.

The experience of separateness arouses anxiety; it is, indeed, the source of all anxiety.

Man's biological weakness is the condition of human culture.

The paradoxical and tragic situation of man is that his conscience is weakest when he needs it most.

I feel worried, deeply worried, only about one thing - the possibility that we fall... that we cannot avoid an atomic war.

An illusion shared by everyone becomes a reality.