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.

Astronomy is so easy to love. ... Fairly or not, physics is associated with nuclear bombs and nuclear waste, chemistry with pesticides, biology with Frankenfood and designer-gene superbabies. But astronomers are like responsible ecotourists, squinting at the scenery through high-quality optical devices, taking nothing but images that may be computer-enhanced for public distribution, leaving nothing but a few Land Rover footprints on faraway Martian soil, and OK, OK, maybe the Land Rover, too.

[On women:] We are all yeses. We are worthy enough, we passed inspection, we survived the great fetal oocyte extinctions. In that sense, at least - call it a mechanospiritual sense - we are meant to be. We are good eggs, every one of us.

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.

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.

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.

evolution is a tinkerer, an ad-hocker, and a jury-rigger. It works with what it has on hand, not with what it has in mind. Some of its inventions prove elegant, while in others you can see the seams and dried glue.