Should I not be proud, when for twenty years I have had to admit to myself that the great Newton and all the mathematicians and noble calculators along with him were involved in a decisive error with respect to the doctrine of color, and that I among millions was the only one who knew what was right in this great subject of nature?

Art is long, life short, judgment difficult, opportunity transient. To act is easy, to think is hard; to act according to our thought is troublesome. Every beginning is cheerful: the threshold is the place of expectation.

The intelligent man finds almost everything ridiculous, the sensible man hardly anything.

The world is so empty if one thinks only of mountains, rivers and cities; but to know someone who thinks and feels with us, and who, though distant, is close to us in spirit, this makes the earth for us an inhabited garden.

if only these treasures were not so fragile as they are precious and beautiful.

A great artist... must be shaken by the naked truths that will not be comforted. This divine discontent, this disequilibrium, this state of inner tension is the source of artistic energy.

Whoever, in middle age, attempts to realize the wishes and hopes of his early youth, invariably deceives himself. Each ten years of a man's life has its own fortunes, its own hopes, its own desires.