Our friends show us what we can do; our enemies teach us what we must do.

A resolution that is communicated is no longer within thy power; thy attentions become now the plaything of chance; he who would have his commands certainly carried out must take man by surprise.

The world is so great and rich, and life so full of variety, that you can never lack occasions for poems.

Rest not. Life is sweeping by; go and dare before you die. Something mighty and sublime, leave behind to conquer time.

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?

Whoever would do good in the world, ought not to deal in censure. We ought not to destroy, but rather construct.

Painting and tattooing the body is a return to animalism.