My muse is male, has the silvery complexion of the moon, and never speaks to me directly. - Diane Ackerman

But, as sages have long said, the sexiest part of the body and the best aphrodisiac in the world is the imagination.

So much of our life passes in a comfortable blur. Living on the senses requires an easily triggered sense of marvel, a little extra energy, and most people are lazy about life. Life is something that happens to them while they wait for death.

We tend to see our distant past through a reverse telescope that compresses it: a short time as hunter-gatherers, a long time as "civilized" people. But civilization is a recent stage of human life, and, for all we know, it may not be any great achievement. It may not even be the final stage. We have been alive on this planet as recognizable humans for about two million years, and for all but the last two or three thousand we’ve been hunter-gatherers. We may sing in choirs and park our rages behind a desk, but we patrol the world with many of a hunter-gatherer’s drives, motives, and skills. These aren’t knowable truths. Should an alien civilization ever contact us, the greatest gift they could give us would be a set of home movies: films of our species at each stage in our evolution.