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.

Curiosity is a delicate little plant that, aside from stimulation, stands mainly in need of freedom.

It stands to the everlasting credit of science that by acting on the human mind it has overcome man's insecurity before himself and before nature.

If people are good because they fear punishment, and hope for reward, then we are a sorry lot indeed.

To raise new questions, new possibilities, to regard old problems from a new angle, requires creative imagination and marks real advance in science.

The ideals which have always shone before me and filled me with the joy of living are goodness, beauty, and truth. To make a goal of comfort or happiness has never appealed to me; a system of ethics built on this basis would be sufficient only for a herd of cattle.

Since the mathematicians have invaded the theory of relativity I do not understand it myself any more.