Painting is poetry that is seen rather than felt, and poetry is painting that is felt rather than seen.

There are many kinds of beauty as people who possess it.

The organ of perception acts more readily than judgment.

The days are long enough for those who use them.

One day the world will look upon research upon animals as it now looks upon research on human beings.

Blinding ignorance does mislead us. O! Wretched mortals, open your eyes!

Although human ingenuity may devise various inventions which, by the help of various instruments, answer to one and the same purpose, yet will it never discover any inventions more beautiful, more simple or more practical than those of nature, because in her inventions there is nothing lacking and nothing superfluous; and she makes use of no counterpoise when she constructs the limbs of animals in such a way as to correspond to the motion of their bodies, but she puts into them the soul of the body.