Imagination is the highest form of research.

The trouble with the younger generation is that they don't stay young for very long.

The theoretical idea ... does not arise apart from and independent of experience; nor can it be derived from experience by a purely logical procedure. It is produced by a creative act. Once a theoretical idea has been acquired, one does well to hold fast to it until it leads to an untenable conclusion.

I never thought that others would take my theories so much more seriously than I did.

Only in mathematics and physics was I, through self-study, far beyond the school curriculum, and also with regard to philosophy as it was taught in the school curriculum.

[I] must seek in the stars that which was denied [to me] on earth.

The more I learn, the more I realize I don't know.