[Alexander von Humboldt was the] greatest scientific traveller who ever lived.

Intelligence is based on how efficient a species became at doing the things they need to survive.

I suppose you are two fathoms deep in mathematics, and if you are, then God help you. For so am I, only with this difference: I stick fast in the mud at the bottom, and there I shall remain.

Formerly Milton's Paradise Lost had been my chief favourite, and in my excursions during the voyage of the Beagle, when I could take only a single small volume, I always chose Milton.

A grand and almost untrodden field of inquiry will be opened, on the causes and laws of variation, on correlation of growth, on the effects of use and disuse, on the direct actions of external conditions, and so forth.

At no time am I a quick thinker or writer: whatever I have done in science has solely been by long pondering, patience and industry.

I think it can be shown that there is such an unerring power at work in Natural Selection, which selects exclusively for the good of each organic being.