The great need to grasp principles had caused me to spend most of my time on fruitless persuits.

One must not attempt to justify them, but rather to sense their nature simply and clearly.

The music of Mozart is of such purity and beauty that one feels he merely found it - that it has always existed as part of the inner beauty of the universe waiting to be revealed.

In theory, theory and practice are the same. In practice, they are not.

Common sense needs constant reappraisal.

Conventional words or other signs have to be sought for laboriously only in a second stage, where the associative play already referred to is sufficiently established and can be reproduced at will.

An attempt at visualizing the Fourth Dimension: Take a point, stretch it into a line, curl it into a circle, twist it into a sphere, and punch through the sphere.