Once again Koestler is out to show us in his literate, calm and clear-eyed fashion how little we know about what we presume to know. Whether, as in The Roots of Coincidence (1972), he is reminding us of the disquieting congruities lately turning up between parapsychology and quantum physics, or mischievously discussing Fischer-Spassky and the rest of that ""fraternity of Passionate Duffers"" who've played (for over 1,000 years now) the game that is a perfect paradigm for ""both the glory and the bloodiness of the human mind,"" or talking about the atavistic hysteria which gripped the French city of Orleans in the wake of a totally unfounded rumor that white slavers were operating there, Koestler is always disturbing, communicating as he does from the shadowy parts of the psyche and then always in understated, soft-spoken tones. In the past few years he has become increasingly convinced that ""the mechanistic and deterministic world view, which is still dominant in sociology and the behavioral sciences and in the public at large no longer has a leg left to stand on."" But unlike the para-science enthusiasts, Koestler is shouting no hosannas. He is more aware of the menace than the promise of the Machine which will inevitably change our ethics, life spans, reproduction. What with genetic engineering, black holes, telepathy and ""cloning"" which can produce ""xerox"" copies of a prize bull, horse or human, after the next Scientific Revolution which Koestler feels is imminent, the future will surely be different. Apocalyptically different. Koestler broods on the phenomena of habituation well-known to scientists -- ""nerve cells in the retina do not signal sameness, they signal only contrast"" -- ambulance crews and the inmates of Auschwitz became accustomed, so to speak, to every sort of mutilation and atrocity. And who knows whether the miracles of technology will make us free men or slaves?