A writer who wishes to be read by posterity must not be averse to putting hints which might give rise to whole books, or ideas for learned discussions, in some corner of a chapter so that one should think he can afford to throw them away by the thousand.

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

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.

The noble simplicity in the works of nature only too often originates in the noble shortsightedness of him who observes it.

The great rule: If the little bit you have is nothing special in itself, at least find a way of saying it that is a little bit special.

In each of us there is a little of all of us.

The construction of the universe is certainly very much easier to explain than is that of the plant.