It is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that is able best to adapt and adjust to the changing environment in which it finds itself.

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

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.

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?

... if variations useful to any organic being do occur, assuredly individuals thus characterized will have the best chance of being perserved in the struggle for life; and from the strong principle of inheritance they will tend to produce offsping similarly characterized. This principle of preservation, I have called, for the sake of brevity, Natural Selection.

I trust and believe that the time spent in this voyage ... will produce its full worth in Natural History; and it appears to me the doing what little we can to increase the general stock of knowledge is as respectable an object of life, as one can in any likelihood pursue.

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.