"The human species is on a thin thread. We're barely making it."

"The pigeon is a better psychologist than the human being because it doesn't have language to confuse it."

"I am sometimes asked, 'Do you think of yourself as you think of the organisms you study?' The answer is yes."

"I did not become a psychologist to cure the sick, but to understand the human condition."

"We need to design a world where people behave well because they want to, not because they have to."