Scientists do not believe in fundamental and absolute certainties. For the scientist, certainty is never an end, but a search; not the ordering of certainty, but its exploration. For the scientist, certainty represents the highest degree of probability.

I want to die young at a ripe old age.

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. All education should be directed toward the refinement of the individual's sensibilities in relation not only to one's fellow humans everywhere, but to all things whatsoever.

The only measure of what you believe is what you do. If you want to know what people believe, don't read what they write, don't ask what they believe, just observe what they do.

The world is so full of wonderful things we should all, if we were taught how to appreciate it, be far richer than kings.

An intelligence that is not humane is the most dangerous thing in the world .

The idea is to die young as late as possible.