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.

Man's external form, marvellously constructed, is not much as compared with the divine soul that dwells inside that structure.

The eye which turns from a white object in the light of the sun and goes into a less fully lighted place will see everything as dark.

I roamed the countryside searching for answers to things I did not understand. Why shells existed on the tops of mountains. How the various circles of water form around the spot which has been struck by a stone, and why a bird sustains itself in the air.

Abbreviators do harm to knowledge and to love.

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

The natural desire of good men is knowledge.