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

Some people come by the name of genius in the same way that certain insects come by the name of centipede -- not because they have a hundred feet, but because most people can't count above 14.

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.

Here take back the stuff that I am, nature, knead it back into the dough of being, make of me a bush, a cloud, whatever you will, even a man, only no longer make me.

The ordinary man is ruined by the flesh lusting against the spirit; the scholar by the spirit lusting too much against the flesh.

A good method of discovery is to imagine certain members of a system removed and then see how what is left would behave: for example, where would we be if iron were absent from the world: this is an old example.

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