Charles Darwin

It is a cursed evil to any man to become as absorbed in any subject as I am in mine.

A moral being is one who is capable of reflecting on his past actions and their motives - of approving of some and disapproving of others.

My mind seems to have become a kind of machine for grinding general laws out of large collections of facts.

The mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an agnostic.

To kill an error is as good a service as, and sometimes even better than, the establishing of a new truth or fact.

I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection.