Soul Made Flesh: The Discovery of the Brain—and How It Changed the World. Carl Zimmer. Free Press, New York, 2004. 384 pp., illus. $26.00 (ISBN 0743230388 cloth).

The end of the world is imminent, spiraling out of control to unavoidable disaster. Loudest are the radical fundamentalists, intolerant, bigoted, deaf to all arguments beyond their narrow ken. It is a time of profound anti-intellectualism, yet, paradoxically, science is in a ferment of creativity. Long-cherished ideas are thrown on furious pyres, leaving worthless ashes to be trampled by careless crowds or blown by meaningless winds. Philosophers no longer discuss abstract precepts in cloistered calm, but engage with the world, questioning every principle, ripping up every foundation. Even the Academy is not immune; the cry goes up to reform radically, once and for all, the ancient universities.

I could, of course, be speaking of today. In fact I am referring to 17th-century England, a country tumbling from the autocracy of the Tudors to the prevarication of the Stuarts, with an interregnum that began with the beheading of a brave but foolish king and ended with the posthumous decapitation of a brave but failed tyrant. The scene of Soul Made Flesh is principally Oxford, and from its shadows of ancient colleges and modern slums step forth both familiar men, notably Christopher Wren, Robert Boyle and William Harvey, and those now poorly remembered, especially Thomas Willis. This was a time of turmoil, of uncertain prospects, when political stars plunged—sometimes to the executioner's block—or soared to heights of aristocratic excess. The defining years of the English Civil Wars might have resembled a bad-tempered picnic compared with the savagery of the religious wars on the adjacent European mainland, but for England they were the single greatest disaster since the annihilation of the Saxon kingdom 600 years earlier. Add disease, culminating in the Great Plague of 1665, and a ferocious criminal system, not to mention a millenniarian spirit of religious zealotry, and one goes some way toward appreciating the backdrop of Carl Zimmer's engrossing account of how mechanism replaced spirit, and how the soul was finally banished to the stuff of dreams, or at least so it appears.

Zimmer's book has many virtues, unsurprisingly given the author's established reputation as a science writer. The first virtue is that Soul Made Flesh is a wonderful read. Carrying the narrative at a brisk pace, it avoids the tendentious word-spinning of much science writing, where the reader is either left gasping for intellectual oxygen or peering through a fog of verbiage. A second virtue is a sympathy for the time in question and the people caught up in a historical process of which they could have little inkling as to its destination. If only that perspective were more common. So too Zimmer is adept at bringing together the luminaries and other actors of the time: Hobbes on his recalcitrant horse, Wren deftly vivisecting a dog, and Anne Greene mysteriously returning to life after hanging. (Readers of Iain Pears's fine novel An Instance of the Fingerpost [Penguin, 1999] will be interested to compare the two books' portrayal of an Oxford far removed from its ongoing Disneyfication and the revival—or was it resurrection?—of the hanged Greene [renamed Sarah Blundy by Pears].)

Zimmer's book has, however, a very definite purpose: It aims to add one more rung to the ladder that, or so it is widely thought, lifts humanity from the miasmic lowlands of superstition and credulity to the shining uplands of rationality. It is a ladder that defines the Enlightenment, but it has the doom of disenchantment, draining the world not only of magic but also of meaning. From our privileged perspective, the path away from the dictates of Galen and Aristotle, and toward the identification of the brain as the seat of mentality, was painfully crooked as investigators heeded the siren calls of Paracelsus and van Helmont, with their empathetic world of alchemy and mysterious forces that were more easily conjured in cabbalistic scribbling than in the retorts and furnaces of their early laboratories. But the result seems inevitable. In essence, the material world was victorious, hinging on the emergence of a mechanistic paradigm. Spurred on by the materialist manifestos of Hobbes, the Oxford scientists approached the human frame with metaphorical screwdrivers and wrenches. As the levers, pistons, and pumps of the body were identified, so the soul evaporated. To Hobbes, there could be no alternative, and he it was who helped prise open the doors to our modern world (and all its attendant horrors). Perhaps, however, we should remember how Boyle insisted that to understand matter gave no explanation of how “the fabric of the Universe” came to be as it is, what determines its utter contingency. Yet, as Zimmer notes, Boyle was worried. If the deepest secrets of the world were revealed, where might the whole process end?

Despite Zimmer's empathy with the denizens of the 17th century, it is clear where his sympathies lie. The alchemist Paracelsus was wrong, but Boyle's notion that “experiments could reveal some of God's language” (p. 135) appealed to another forlorn hope. Zimmer's account is also triumphalist as he catapults the reader from the mire of 17th-century England to the clinical austerity of the modern laboratory, where powerful magnets and computers combine to reveal the brain's cartography, where mind is revealed in (and reduced to) flashing lights. Observing, however, is not necessarily equivalent to understanding. To know that one part of my brain “lights up” when I think of a stiff gin-and-tonic, and another when I write this review, is certainly fascinating. But are we any closer to understanding what makes us sentient?

Zimmer observes that when the hanged Greene returned to life, by whatever route, she began again her gallows-side speech, but otherwise all memory of her terrible ordeal had fled. To say on this basis that memory is mechanical surely misses the point. Think of those memories that surface after decades of absence, returning with an eerie vividness. The simple fact is that we are still as far as ever from understanding how the mush of neurons actually creates and recalls our reality. Even when all parts of the brain are mapped to the nth degree, there is no prospect in sight that mind itself will emerge from the neural shadows. The question is simply different.

So too with the apparently nebulous soul. To talk of banishing it really misses the point, because it presupposes a medie val outlook that was never worth defending. As the philosopher Stephen Clark reminds us, the classic parody of medieval thought, about how many angels can dance on the head of a pin, is answered, “Just as many as they please.” Angels, just in case you had forgotten, are, as Clark writes, “immaterial intellects [that] do not occupy space to the exclusion of any such intellectual substance.” In an analogous way, the same applies to the brain and the soul. The former remains concrete but deeply mysterious, the latter elusive but deeply familiar.