"The greatest discovery of all time is that a person can change his future by merely changing his attitude."

"Man in his arrogance thinks himself a great work, worthy of the interposition of a deity. More humble and I believe truer to consider him created from animals."

"I hate a Barnacle as no man ever did before, not even a Sailor in a slow-sailing ship."

"Man, with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect…"

"I am almost convinced (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable."