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.

Patriotism is the willingness to kill and be killed for trivial reasons.

The method of "postulating" what we want has many advantages; they are the same as the advantages of theft over honest toil.

Freedom comes only to those who no longer ask of life that it shall yield them any of those personal goods that are subject to the mutations of time.

Remote from human passions, remote even from the pitiful facts of nature, the generations have gradually created an ordered cosmos [mathematics], where pure thought can dwell in its natural home.

Zeno was concerned with three problems... These are the problem of the infinitesimal, the infinite, and continuity.

An extra-terrestrial philosopher, who had watched a single youth up to the age of twenty-one and had never come across any other human being, might conclude that it is the nature of human beings to grow continually taller and wiser in an indefinite progress towards perfection; and this generalization would be just as well founded as the generalization which evolutionists base upon the previous history of this planet.