We still think of human disease as the work of an organized, modernized kind of demonology, in which the bacteria are the most visible and centrally placed of our adversaries. We assume that they must somehow relish what they do.

The human mind is not meant to be governed, certainly not by any book of rules yet written; it is supposed to run itself, and we are obliged to follow it along, trying to keep up with it as best we can.

The drive to be useful is encoded in our genes. But when we gather in very large numbers, as in the modern nation-state, we seem capable of levels of folly and self-destruction to be found nowhere else in all of nature. But if we keep at it and keep alive, we are in for one surprise after another. We can build structures for human society never seen before, thoughts never heard before, music never heard before.

The earliest sensation at the onset of illness, often preceding the recognition of identifiable symptoms, is apprehension. Something has gone wrong, and a glimpse of mortality shifts somewhere deep in the mind. It is the most ancient of our fears.

As a species, taking all in all, we are still too young, too juvenile, to be trusted. We have spread across the face of the earth in just a few thousand years, no time at all as evolution clocks time, covering all livable parts of the planet, endangering other forms of life, and now threatening ourselves.

We leave traces of ourselves wherever we go, on whatever we touch.

Viewed from the distance of the moon, the astonishing thing about the earth, catching the breath, is that it is alive. ... It has the organized, self-contained look of a live creature, full of information, marvelously skilled in handling the sun