"A first principle of behavior is that it is shaped by its consequences."

"The way in which we think about the causes of human behavior has changed in a way that suggests that we are at an early stage of a scientific revolution."

"The problem is not to get students to ask questions, but to get them to ask interesting questions."

"No one asks how to motivate a baby. A baby naturally explores everything it can get at, unless restraining forces have already been at work. And what is true of the baby is true of the scientist."

"The only difference between rats and people is that rats learn from experience."