If people are good because they fear punishment, and hope for reward, then we are a sorry lot indeed.
A happy man is too satisfied with the present to dwell too much on the future.
The greater the doubt, the greater the awakening
You can never solve a problem with the same kind of thinking that created the problem in the first place.
What you can't imagine, you can't discover.
Since I have introduced this term I had always a bad conscience. . . . I cannot help to feel it strongly and I am unable to believe that such an ugly thing should be realized in nature.