Real knowledge is to know the extent of one's ignorance. – Confucius

Knowledge has three degrees: opinion, science, illumination. The means or instrument of the first is sense; of the second, dialectic; of the third, intuition. – Plotinus

It is the province of knowledge to speak, and it is the privilege of wisdom to listen. – Oliver Wendell Holmes, Jr.

I would rather excel others in the knowledge of what is excellent than in the extent of my powers and dominion. – Alexander III of Macedon (Alexander the Great)

There is nothing with which every man is so afraid as getting to know how enormously much he is capable of doing and becoming. – Soren Kierkegaard

The improvement of understanding is for two ends: first, our own increase of knowledge; secondly, to enable us to deliver that knowledge to others. – John Locke

We are now at a point where we must educate our children in what no one knew yesterday, and prepare our schools for what no one knows yet. – Margaret Mead

The greatest lesson in life is to know that even fools are right sometimes. – Horace

A good decision is based on knowledge and not on numbers. – Plato

Opinion is the medium between knowledge and ignorance. – Plato

The learning and knowledge that we have, is, at the most, but little compared with that of which we are ignorant. – Plato

To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge. – Nicolaus Copernicus

Mankind have a great aversion to intellectual labor; but even supposing knowledge to be easily attainable, more people would be content to be ignorant than would take even a little trouble to acquire it. – Samuel Johnson

Iron rusts from disuse; stagnant water loses its purity and in cold weather becomes frozen; even so does inaction sap the vigor of the mind. – Leonardo Da Vinci

The world is governed more by appearances than realities, so that it is fully as necessary to seem to know something as to know it. – Daniel Webster