"I could show fight on natural selection having done and doing more for the progress of civilization than you seem inclined to admit."

"I have tried lately to read Shakespeare, and found it so intolerably dull that it nauseated me."

"Man tends to increase at a greater rate than his means of subsistence."

"There is no fundamental difference between man and the higher mammals in their mental faculties."

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