We are like a rider on top of a gigantic elephant. We can steer the elephant, and if he's not busy, he'll go where we want, but if he has other desires, he'll often go where he wants. How can one control the elephant? In part, this comes with maturity. In part, this comes with the development of your frontal cortex, so the frontal areas of the brain are especially involved in self-control, in suppressing your initial instinct to act. This is why teenagers are so impulsive. So it's terrible to allow the death penalty for teenagers, because they really don't have working brains yet.

I'll suggest that the happiness hypothesis offered by Buddha and the Stoics should be amended: Happiness comes from within, and happiness comes from without. We need the guidance of both ancient wisdom and modern science to get the balance right.

It only takes twenty generations of selective breeding to create large differences or appearance and behavior in other mammals.

I think the greatest work in social psychology from the 1950s and '60s is enormously important. I wish every high school kid could take a course in social psychology. I think we're making enormous strides in understanding the brain. These aren't yet giving us great insights, but I feel like we're on the verge of it. In five or ten years this basically searching the brain is really going to change things.

People can believe pretty much whatever they want to believe about moral and political issues, as long as some other people near them believe it, so you have to focus on indirect methods to change what people want to believe.

The extreme self-sacrifice characteristic of group-selected species such as ants and bees can often be found among soldiers.

We can call this "the progress principle": Pleasure comes more from making progress toward goals than from achieving them. Shakespeare captured it perfectly: "Things won are done; joy's soul lies in the doing."