The proof that man is the noblest of all creatures is that no other creature has ever denied it.

It thunders, howls, roars, hisses, whistles, blusters, hums, growls, rumbles, squeaks, groans, sings, crackles, cracks, rattles, flickers, clicks, snarls, tumbles, whimpers, whines, rustles, murmurs, crashes, clucks, to gurgle, tinkles, blows, snores, claps, to lisp, to cough, it boils, to scream, to weep, to sob, to croak, to stutter, to lisp, to coo, to breathe, to clash, to bleat, to neigh, to grumble, to scrape, to bubble. These words, and others like them, which express sounds are more than mere symbols: they are a kind of hieroglyphics for the ear.

A man of spirit must not think of the word difficulty as so much as existing. Away with it!

If there were only turnips and potatoes in the world, someone would complain that plants grow the wrong way.

What you have been obliged to discover by yourself leaves a path in your mind which you can use again when the need arises.

People who have read a good deal rarely make great discoveries. I do not say this in excuse of laziness, but because invention presupposes an extensive independent contemplation of things.

Astronomy is perhaps the science whose discoveries owe least to chance, in which human understanding appears in its whole magnitude, and through which man can best learn how small he is.