Not ignorance, but ignorance of ignorance, is the death of knowledge.

The deepest definition of youth is life as yet untouched by tragedy.

Philosophy begins in wonder. And, at the end, when philosophic thought has done its best, the wonder remains.

The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato.

It is in literature that the concrete outlook of humanity receives its expression.

In formal logic, a contradiction is the signal of defeat, but in the evolution of real knowledge it marks the first step in progress toward a victory.

The task of a university is the creation of the future, so far as rational thought and civilized modes of appreciation can affect the issue.

The vitality of thought is in adventure. Ideas won't keep. Something must be done about them. When the idea is new, its custodians have fervor, live for it, and if need be, die for it.

Without adventure civilization is in full decay.

Civilizations can only be understood by those who are civilized.

No period of history has ever been great or ever can be that does not act on some sort of high, idealistic motives, and idealism in our time has been shoved aside, and we are paying the penalty for it.

It requires a very unusual mind to undertake the analysis of the obvious.

Life is an offensive, directed against the repetitious mechanism of the Universe.

No one who achieves success does so without acknowledging the help of others. The wise and confident acknowledge this help with gratitude.

Speech is human nature itself, with none of the artificiality of written language.

But you can catch yourself entertaining habitually certain ideas and setting others aside; and that, I think, is where our personal destinies are largely decided.

It is the business of the future to be dangerous; and it is among the merits of science that it equips the future for its duties.

There are no whole truths: all truths are half-truths. It is trying to treat them as whole truths that plays to the devil.

Man can acquire accomplishments or he can become an animal, whichever he wants. God makes the animals, man makes himself.

Knowledge shrinks as wisdom grows.

Our minds are finite, and yet even in these circumstances of finitude we are surrounded by possibilities that are infinite, and the purpose of life is to grasp as much as we can out of that infinitude.

Philosophy is the product of wonder.

An enormous part of our mature experience cannot not be expressed in words.

Ideas won't keep; something must be done about them.

Intelligence is quickness to apprehend as distinct form ability, which is capacity to act wisely on the thing apprehended.

Periods of tranquility are seldom prolific of creative achievement. Mankind has to be stirred up.

Fools act on imagination without knowledge, pedants act on knowledge without imagination.

Familiar things happen, and mankind does not bother about them. It requires a very unusual mind to undertake the analysis of the obvious.

Almost all new ideas have a certain aspect of foolishness when they are first produced.

It takes an extraordinary intelligence to contemplate the obvious.

Civilization advances by extending the number of important operations which we can perform without thinking of them.

The art of progress is to preserve order amid change and to preserve change amid order.

We think in generalities, but we live in detail.

Simple solutions seldom are. It takes a very unusual mind to undertake analysis of the obvious.

Wisdom alone is true ambition's aim, wisdom is the source of virtue and of fame; obtained with labour, for mankind employed, and then, when most you share it, best enjoyed.

I have suffered a great deal from writers who have quoted this or that sentence of mine either out of its context or in juxtaposition to some incongruous matter which quite distorted my meaning, or destroyed it altogether.

True courage is not the brutal force of vulgar heroes, but the firm resolve of virtue and reason.

What is morality in any given time or place? It is what the majority then and there happen to like and immorality is what they dislike.

Human life is driven forward by its dim apprehension of notions too general for its existing language.

Common sense is genius in homespun.

Seek simplicity but distrust it.

The absolute pacifist is a bad citizen; times come when force must be used to uphold right, justice and ideals.

Art attracts us only by what it reveals of our most secret self.

If a dog jumps into your lap, it is because he is fond of you; but if a cat does the same thing, it is because your lap is warmer.

The total absence of humor from the Bible is one of the most singular things in all literature.

I would be a billionaire if I was looking to be a selfish boss. That's not me.

Art flourishes where there is a sense of adventure.

The guiding motto in the life of every natural philosopher should be, seek simplicity and distrust it.

Not ignorance, but ignorance of ignorance, is the death of knowledge.