The candle flame gutters. Its little pool of light trembles. Darkness gathers. The demons begin to stir.

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

In the fabric of space and in the nature of matter, as in a great work of art, there is, written small, the artist's signature.

Imagine we could accelerate continuously at 1 g-what we're comfortable with on good old terra firma-to the midpoint of our voyage, and decelerate continuously at 1 g until we arrive at our destination. It would take a day to get to Mars, a week and a half to Pluto, a year to the Oort Cloud, and a few years to the nearest stars.

We on Earth have just awakened to the great oceans of space and time from which we have emerged.

But down deep, at the molecular heart of life we're essentially identical to trees.

For all its material advantages, the sedentary life has left us edgy, unfulfilled, even after 400 generations in villages and cities, we haven't forgotten: The open road still softly calls like a nearly forgotten song of childhood.