Perhaps eggs are like neurons, which also are not replenished in adulthood: they know too much. Eggs must plan the party. Sperm need only to show up- wearing top hat and tails, of course.

Scientists have discovered that the small, brave act of cooperating with another person, of choosing trust over cynicism, generosity over selfishness, makes the brain light up with quiet joy.

The surest and most insidious enemy of freedom is not dictatorship, but complacency.

When I sent out a casual and nonscientific poll of my own to a wide cast of acquaintances, friends and colleagues, I was surprised, but not really, to learn that maybe 60 percent claimed a belief in a God of some sort, including people I would have bet were unregenerate skeptics. Others just shrugged. They don't think about this stuff. It doesn't matter to them. They can't know, they won't beat themselves up trying to know and for that matter they don't care if their kids believe or not.

scientists ... resist ... making more of the data than the data make of themselves.

Science is not a body of facts. Science is a state of mind. It is a way of viewing the world, of facing reality square on but taking nothing on its face. It is about attacking a problem with the most manicured of claws and tearing it down into sensible, edible pieces.

Nature is a tenacious recycler, every dung heap and fallen redwood tree a bustling community of saprophytes wresting life from the dead and discarded, as though intuitively aware that there is nothing new under the sun. Throughout the physical world, from the cosmic to the subatomic, the same refrain resounds. Conservation: it's not just a good idea, it's the law.