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

"The very existence of our senses, our reason, and our intellect, is a proof that these faculties were given us for some purpose."

"In the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed."

"The more I see of the world, the more I am convinced of the fact that it is full of wonders."

"The expression of the emotions in man and animals is a study of the utmost interest."