Nature hides her secrets because of her essential loftiness, but not by means of ruse.

The indifference, callousness and contempt that so many people exhibit toward animals is evil first because it results in great suffering in animals, and second because it results in an incalculably great impoverishment of the human spirit.

My scientific work is motivated by an irresistible longing to understand the secrets of nature not by other feelings.

... one does people the best service by giving them some elevating work to do and thus indirectly elevating them.

The stakes are immense, the task colossal, the time is short. But we may hope - we must hope - that man's own creation, man's own genius, will not destroy him.

Figuring out how to think about the problem.

Well-being and happiness never appeared to me as an absolute aim. I am even inclined to compare such moral aims to the ambitions of a pig.