“Know yourself to improve yourself.”

The heavens declare the glory of Kepler and Newton.

Each department of knowledge passes through three stages. The theoretic stage; the theological stage and the metaphysical or abstract stage.

In mathematics we find the primitive source of rationality; and to mathematics must the biologists resort for means to carry out their researches.

The sacred formula of positivism: love as a principle, the order as a foundation, and progress as a goal.

Monotheism occupies so large a space in the view of modern minds, that it is scarcely possible to form a just estimate of the preceding phases of the theological philosophy.

All good intellects have repeated, since Bacon’s time, that there can be no real knowledge but which is based on observed facts.

Religion is an illusion of childhood, outgrown under proper education.

If we do not allow free thinking in chemistry or biology, why should we allow it in morals or politics?

Mathematical Analysis is… the true rational basis of the whole system of our positive knowledge.

Nothing is destroyed until it is replaced.

The dead govern the living.

Woman is the most moral element in all humanity.

The word right should be excluded from political language, as the word cause from the language of philosophy.

Men are not allowed to think freely about chemistry and biology: why should they be allowed to think freely about political philosophy?

The universe displays no proof of an all-directing mind.

Humanity is always made up of more dead than living.

You know you love someone when you cannot put into words how they make you feel.

Absolute power, as we have always known, corrupts absolutely; it corrupts because it does not do the trick for the individual.

The wise man, knowing how to enjoy achieved results without having constantly to replace them with others, finds in them an attachment to life in the hour of difficulty.

I do not know which makes a man more conservative – to know nothing but the present, or nothing but the past.

We must declare ourselves, become known; allow the world to discover this subterranean life of ours which connects kings and farm boys, artists and clerks. Let them see that the important thing is not the object of love, but the emotion itself.

Is it possible that nobody has ever known that there never has been a completely civilized man, and won’t be for another thousand years?

The considerations upon which expectations of prospective yields are based are partly existing facts which we can assume to be known more or less for certain, and partly future events which can only be forecasted with more or less confidence.

Presidents in both parties – from John F. Kennedy to Ronald Reagan – have known that our free-enterprise economy is the source of our middle-class prosperity.