Man owes his strength in the struggle for existence to the fact that he is a social animal.

When you sit with a nice girl for two hours, it seems like two minutes; when you sit on a hot stove for two minutes, it seems like two hours. That's relativity.

The more a country makes military weapons, the more insecure it becomes: if you have weapons, you become a target for attack.

Nevertheless, it is necessary to remember that a planned economy is not yet socialism. A planned economy as such may be accompanied by the complete enslavement of the individual. The achievement of socialism requires the solution of some extremely difficult socio-political problems: how is it possible, in view of the far-reaching centralisation of political and economic power, to prevent bureaucracy from becoming all-powerful and overweening? How can the rights of the individual be protected and therewith a democratic counterweight to the power of bureaucracy be assured?

No path leads from a knowledge of that which is to that which should be.

I believe my theory of relativity to be true. But it will only be proved for certain in 1981, when I am dead.

There is not the slightest indication that nuclear energy will ever be obtainable. It would mean that the atom would have to be shattered at will.