A man should look for what is, and not for what he thinks should be.

Whether or not you can observe a thing depends upon the theory you use. It is the theory which decides what can be observed.

We owe a lot to the Indians, who taught us how to count, without which no worthwhile scientific discovery could have been made.

Adversity introduces a man to himself.

If a theory can not be explained to a child, then the theory is probably worthless.

Intellectuals solve problems, geniuses prevent them.

Violence sometimes may have cleared away obstructions quickly, but it never has proved itself creative.