But then with me the horrid doubt always arises whether the convictions of man's mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey's mind, if there are any convictions in such a mind?

Man is developed from an ovule, about 125th of an inch in diameter, which differs in no respect from the ovules of other animals.

I have steadily endeavored to keep my mind free so as to give up any hypothesis, however much beloved (and I cannot resist forming one on every subject), as soon as the facts are shown to be opposed to it.

It has sometimes been said that the success of the Origin proved "that the subject was in the air," or "that men's minds were prepared for it." I do not think that this is strictly true, for I occasionally sounded not a few naturalists, and never happened to come across a single one who seemed to doubt about the permanence of species.

Farewell Australia! You ... are too great and ambitious for affection, yet not great enough for respect. I leave your shores without sorrow or regret.

[Herschel and Humboldt] stirred up in me a burning zeal to add even the most humble contribution to the noble structure of Natural Science. No one or a dozen other books influenced me nearly so much as these two. I copied out from Humboldt long passages about Teneriffe and read them aloud on one of [my walking excursions].

Not one great country can be named, from the polar regions in the north to New Zealand in the south, in which the aborigines do not tattoo themselves.