The only measure of what you believe is what you do.

The scientist believes in proof without certainty.

Do we have the right to rear animals in order to kill them so that we may feed appetites in which we have been artificially conditioned from childhood?

The scientist believes in proof without certainty, the bigot in certainty without proof.

The deepest personal defeat suffered by human beings is constituted by the difference between what one was capable of becoming and what one has in fact become.

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 living things whatsoever.

Human beings are the only creatures who are able to behave irrationally in the name of reason.