All the fifty years of conscious brooding have brought me no closer to answer the question, "What are light quanta?" Of course today every rascal thinks he knows the answer, but he is deluding himself.

Only morality in our actions can give beauty and dignity to life.

Strive not to be a success, but rather to be of value.

Why does this magnificent applied science which saves work and makes life easier bring us so little happiness? ... The simple answer runs: 'Because we have not yet learned to make sensible use of it.'

On the left-hand side of the field equation we may add the fundamental tensor guv, multiplied by a universal constant, -λ, at present unknown, without destroying the general covariance.

A scientist is a mimosa when he himself has made a mistake, and a roaring lion when he discovers a mistake of others.

Highly developed spirits often encounter resistance from mediocre minds.