Science does not aim at establishing immutable truths and eternal dogmas; its aim is to approach the truth by successive approximations, without claiming that at any stage final and complete accuracy has been achieved.

Thinking you know when in fact you don't is a fatal mistake, to which we are all prone

My doctor said to me afterwards, 'When you were ill you behaved like a true philosopher. Every time you came to yourself you made a joke.' I never had a compliment that pleased me more.

In action, in desire, we must submit perpetually to the tyranny of outside forces; but in thought, in aspiration, we are free, free from our fellowmen, free from the petty planet on which our bodies impotently crawl, free even, while we live, from the tyranny of death.

The key to happiness is accepting one unpleasant reality every day.

The conception of the necessary unit of all that is resolves itself into the poverty of the imagination, and a freer logic emancipates us from the straitwaistcoated benevolent institution, which idealism palms off as the totality of being.

I believe that the abolition of private ownership of land and capital is a necessary step toward any world in which the nations are to live at peace with one another.