After my return to England it appeared to me that by following the example of Lyell in Geology, and by collecting all facts which bore in any way on the variation of animals and plants under domestication and nature, some light might perhaps be thrown on the whole subject.

I can indeed hardly see how anyone ought to wish Christianity to be true for if so the plain language of the text seems to show that the men who do not believe, and this would include my father, brother and almost all of my friends, will be everlastingly punished. And this is a damnable doctrine.

I have long discovered that geologists never read each other's works, and that the only object in writing a book is a proof of earnestness.

Our descent, then, is the origin of our evil passions!! The devil under form of Baboon is our grandfather.

Thus we have given to man a pedigree of prodigious length, but not, it may be said, of noble quality.

...I feel most deeply that the whole subject is too profound for the human intellect. A dog might as well speculate on the mind of Newton.— Let each man hope & believe what he can.—

The following proposition seems to me in a high degree probable—namely, that any animal whatever, endowed with well-marked social instincts, the parental and filial affections being here included, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well, or nearly as well developed, as in man. For, firstly, the social instincts lead an animal to take pleasure in the society of its fellows, to feel a certain amount of sympathy with them, and to perform various services for them.