I have only two rules which I regard as principles of conduct. The first is: Have no rules. The second is: Be independent of the opinion of others.

The gift of fantasy has meant more to me than my talent for absorbing positive knowledge.

Marvellous, what ideas the young people have these days. But I don't believe a word of it.

It is true that the grasping of truth is not possible without empirical basis. However, the deeper we penetrate and the more extensive and embracing our theories become the less empirical knowledge is needed to determine those theories.

I like to think the moon is there even if I am not looking at it.

No one must think that Newton’s great creation can be overthrown in any real sense by this [Theory of Relativity] or by any other theory. His clear and wide ideas will for ever retain their significance as the foundation on which our modern conceptions of physics have been built.

Desire for approval and recognition is a healthy motive, but the desire to be acknowledged as better, stronger, or more intelligent than a fellow being or fellow scholar easily leads to an excessively egoistic psychological adjustment, which may become injurious for the individual and for the community.