I am convinced that natural selection has been the main but not exclusive means of modification. - Charles Darwin

As far as I can judge, I am not apt to follow blindly the lead of other men. I have steadily endeavoured 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 facts are shown to be opposed to it. Indeed I have had no choice but to act in this manner, for with the exception of the Coral Reefs, I cannot remember a single first-formed hypothesis which had not after a time to be given up or greatly modified. This has naturally led me to distrust greatly deductive reasoning in the mixed sciences.

The highest stage in moral culture at which we can arrive, is when we recognise that we ought to control our thoughts.

The limit of man s knowledge in any subject possesses a high interest which is perhaps increased by its close neighbourhood to the realms of imagination.