I would give absolutely nothing for the theory of Natural Selection, if it requires miraculous additions at any one stage of descent.

Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, in its infinitely complex relationship to other organic beings and to external nature, will tend to the preservation of that individual, and will generally be inherited by its offspring.

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.

An agnostic would be the more correct description of my state of mind.

Often a cold shudder has run through me, and I have asked myself whether I may have not devoted myself to a fantasy.

The formation of different languages and of distinct species and the proofs that both have been developed through a gradual process, are curiously parallel.

We may confidently come to the conclusion, that the forces which slowly and by little starts uplift continents, and that those which at successive periods pour forth volcanic matter from open orifices, are identical.