The most important method of education always has consisted of that in which the pupil was urged to actual performance.

Every serious scientific worker is painfully conscious of this involuntary relegation to an ever-narrowing sphere of knowledge, which threatens to deprive the investigator of his broad horizon and degrades him to the level of a mechanic.

Nationalism is an infantile disease. It is the measles of mankind.

Subtle is the Lord. Malicious, He is not.

Great spirits have always encountered opposition from mediocre minds. The mediocre mind is incapable of understanding the man who refuses to bow blindly to conventional prejudices and chooses instead to express his opinions courageously and honestly.

I have no special talent. I am only passionately curious. The important thing is to not stop questioning. Curiousity has its own reason for existing.

Formerly, people thought that if matter disappeared from the universe, space and time would remain. Relativity declares that space and time would disappear with matter.