If I give you a pfennig, you will be one pfennig richer and I'll be one pfennig poorer. But if I give you an idea, you will have a new idea, but I shall still have it too.

Some men spend a lifetime in an attempt to comprehend the complexities of women. Others pre-occupy themselves with somewhat simpler tasks, such as understanding the theory of relativity!

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

The human mind has first to construct forms, independently, before we can find them in things.

It is characteristic of the military mentality that non-human factors ... are held essential, while the human being, his desires and thoughts-in short, the psychological factors-are considered as unimportant and secondary.

Scientific greatness is less a matter of intelligence than character; if the scientist refuses to compromise or accept incomplete answers and persists in grappling the most basic and difficult questions.

Now to the term 'relativity theory.' I admit that it is unfortunate, and has given occasion to philosophical misunderstandings.