Rest enough for the individual man, too much and too soon, and we call it death. But for man, no rest and no ending. He must go on, conquest beyond conquest. First this little planet and all its winds and ways, and then all the laws of mind and matter that restrain him. Then the planets about him, and, at last, out across immensities to the stars. And when he has conquered all the deep space, and all the mysteries of time, still he will be beginning.

We live in reference to past experience and not to future events, however inevitable.

Nothing remains interesting where anything may happen.

The ethical system of these men of the New Republic, the ethical system which will dominate the world state, will be shaped primarily to favour the procreation of what is fine and efficient and beautiful in humanity — beautiful and strong bodies, clear and powerful minds, and a growing body of knowledge — and to check the procreation of base and servile types, of fear-driven and cowardly souls, of all that is mean and ugly and bestial in the souls, bodies, or habits of men.

...the voice was indisputable. It continued to swear with that breadth and variety that distinguishes the swearing of a cultivated man.

There is no upper limit to what individuals are capable of doing with their minds. There is no age limit that bars them from beginning. There is no obstacle that cannot be overcome if they persist and believe.

I never yet heard of a useless thing that was not ground out of existence by evolution sooner or later. Did you? And pain gets needless.