... 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.

Light may be shed on man and his origins.

It at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed.

The most important factor in survival is neither intelligence nor strength but adaptability.

Disbelief crept over me at a very slow rate, but at last it was complete.

The several difficulties here discussed, namely our not finding in the successive formations infinitely numerous transitional links between the many species which now exist or have existed; the sudden manner in which whole groups of species appear in our European formations; the almost entire absence, as at present known, of fossiliferous formations beneath the Silurian strata, are all undoubtedly of the gravest nature.

we are always slow in admitting any great change of which we do not see the intermediate steps