Only six men in the world know about relativity. I am not one of them. When I ask them to explain, they confused me.

It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure.

All men are ignorant, just in different fields.

The future is an unknown, but a somewhat predictable unknown. To look to the future we must first look back upon the past. That is where the seeds of the future were planted. I never think of the future. It comes soon enough.

Dear Posterity, If you have not become more just, more peaceful, and in general more sensible... then may the Devil take you!

[Freud's] sense of reality is less clouded by wishful thinking than is the case with other people and [he combines] the qualities of critical judgment, earnestness and responsibility.

Three Rules of Work: Out of clutter find simplicity. From discord find harmony. In the middle of difficulty lies opportunity.