The secret of happiness is variety, but the secret of variety, like the secret of all spices, is knowing when to use it.

The human brain is the only object in the known universe that can predict its own future and tell its on fortune. The fact that we can make disastrous decisions even as we foresee their consequences is the great, unsolved mystery of human behavior. When you hold your fate in your hands, why would you ever make a fist?

The fact that we often judge the pleasure of an experience by its ending can cause us to make some curious choices.

Part of us believes the new car is better because it lasts longer. But, in fact, that's the worst thing about the new car. It will stay around to disappoint you, whereas a trip to Europe is over. It evaporates. It has the good sense to go away, and you are left with nothing but a wonderful memory.

When we have an experience -- hearing a particular sonata, making love with a particular person, watching the sun set from a particular window of a particular room -- on successive occasions, we quickly begin to adapt to it, and the experience yields less pleasure each time. Psychologists call this habituation, economists call it declining marginal utility, and the rest of us call it marriage

Impact is rewarding. Mattering makes us happy.

Arthritic toothless people who love orgasms are more likely to reproduce than are limber, toothy people who do not.