Pythagoras

Do not say a little in many words but a great deal in few. The highest form of knowledge is to know yourself. Choose rather to be strong in soul than in body.

All is number. The universe is written in the language of mathematics — the harmony of the spheres, the ratios of music, the proportions of the human body. To know number is to know God.

As long as man continues to be the ruthless destroyer of living beings, he will never know health or peace. For as long as men massacre animals, they will kill each other.

Numbers are the rulers of the universe. In right triangles the square of the hypotenuse equals the sum of the squares of the other two sides — this I do not claim to have discovered but I claim to have proved it. The Babylonians knew the numerical relationship for centuries; what they lacked was the demonstration that it is necessarily true for all right...

The highest form of purification is philosophy. The soul imprisoned in the body has lived before and will live again, passing through many forms. The philosopher, by contemplating eternal truths — the harmonies of number, the ratios of music, the geometry of the cosmos — begins to free the soul from its material entanglement and returns it toward the...

Number is the ruler of forms and ideas and the cause of gods and daemons. When I say this I do not mean number as calculation. I mean number as proportion, harmony, structure — the invisible skeleton of the world that becomes visible only to those who have trained their minds to see it.

The most momentous thing in human life is the art of winning the soul to good or to evil. I taught my students to examine themselves before they slept each night: Where did I fail? What did I accomplish? What duty left undone? The examined day is the only path to the examined life.

Educate the children and it won't be necessary to punish the men. Vice is not inborn — it is taught by example, by neglect, and by the early absence of beauty and proportion. A city that educates well needs fewer prisons and fewer soldiers.

Friends have all things in common. The school I established at Croton was built on this principle: property held in common, meals shared, knowledge not hoarded. The man who learns only for himself teaches nothing and illuminates no one.

Above all things, reverence thyself. Not from vanity, but because the self that is worthy of reverence is the self that has been shaped by reason, disciplined by practice, and oriented toward the good. What you worship tells you what you believe yourself to be worth.

The universe is a living harmony. When you hear music that moves you, you are hearing the same ratios that govern the distances of the planets. I did not discover this by chance. I was listening — to strings, to spheres, to the intervals that organise everything that exists.

Raphael painted me in the lower-left of his fresco, writing in a book, young men looking over my shoulder. He put me near Euclid and beside a tablet showing the musical ratios: the tetractys, the proportions of the octave, the fourth, the fifth. He understood what I taught: that number is not a tool for measuring things but the substance of which things...