"It is always best to be a little under rather than over the mark."

"At some future period, not very distant as measured by centuries, the civilized races of man will almost certainly exterminate and replace the savage races throughout the world."

"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."

"The love for all living creatures is the most noble attribute of man."

"I have been much struck by the fact that the more I have read about the subject, the less I have understood it."