Even in the age of machines, "soul" remains a viable concept.
In fact, back in 1981 Tracy Kidder published a book called The Soul of a New Machine, an account of the genesis of the Data General Eclipse computer.
Whether a computer can be said to have a soul is, well, iffy, although the MacBook Air comes pretty close, given not only its technological wizardry and aesthetic purity, but also its apparent ability to send its owners into a state of rapture.
I had no compunctions about calling one of my books The Soul of the Night: An Astronomical Pilgrimage, and subtitling another Essays in Search of the Soul of Science. The night and science are entities whose essences escape any descriptions we might formulate. Both night and science are complex and elusive, their souls the object of pilgrimage and search.
And don't forget soul music, soul food, and soul brother or sister.
Soul is the measure of a thing whose borders are hard to define in space or time.
My MacBook is pretty well backed up, and if it dies I should be able to fill another machine with the photographic and verbal record of my life that is stored in its hard drive. Those photos, e-mails, books and essays are part of my soul. I don't expect them to endure forever, but surely some part of them will survive my death. My living essence will have leaked into the future, just as it has stained the past.
Increasingly, our souls are transmogrified or appropriated onto the internet, a thing that might fairly be called the world soul. Perhaps it is the world soul -- the collective human soul -- that will be immortal, as Teilhard de Chardin imagined. Already some part of the world soul has leaked into space, as radio waves a hundred light-years away, and as spacecraft that are exiting the solar system.
Meanwhile, I cultivate my own soul, whatever it is that makes me uniquely me, as a gardener might tend a favorite plant, watering it with whatever love I can garner from family and friends, fertilizing it with the works and wisdom of others, exposing it to the sunshine of those of you who kindly visit this blog.