Operating-room errors hold a special terror for patients, if only because they seem like the most avoidable kind of complications. The occasional horror stories of patients who have the wrong leg removed or the wrong knee replaced generate the most headlines, as do tales of patients whose identities are mixed up entirely.

Introverts listen better, they assess risks more carefully, they can be wiser managers. It's not for nothing that the Silicon Valley billionaires are so often the retiring types.

No one ever pretended that shopping for anything is a rational experience. If it were, would there be Fluffernutter? Laceless sneakers? Porkpie hats? Would the Chia Pet even exist?

Becoming food savvy is one thing, but it's amazing how fast savvy turns to snooty, and snooty leaves you preparing three-hour meals that break your budget and that the kids won't even eat.

Indeed, the best way to think of willpower is not as some shapeless behavioral trait but as a sort of psychic muscle, one that can atrophy or grow stronger depending on how it's used.

Scarily, football helmets, which do a fine job of protecting against scalp laceration and skull fracture, do little to prevent concussions and may even exacerbate them, since even as the brain is rattling around inside the skull, the head is rattling around inside the helmet.

Toxins love to get you while you're young. Lead, mercury, secondhand smoke and sundry other environmental nasties do a lot more damage when tissue is immature, vulnerable and growing than when it's mature and comparatively fixed.