Debates about the "soul" have raged for millennia. Because we tend to think these debates are confined to the realms of philosophy and theology, we ignore the contribution medicine has made to our perception of the "self". Carl Zimmer's examination of the debate and its significant participants enlarges our outlook. His depiction of the life of Thomas Willis in tumultuous 17th Century Britain reveals the pioneering research that lead to a new view of the body's functions. The "soul", so long a mysterious concept, began to be exposed in the brain and its relation to the rest of the body. The study of illnesses, particularly those associated with behaviour, disclosed how false traditional views truly were.
The ancients, Zimmer explains, had varying ideas about the body's workings. He summarises the many views, noting how certain ancient thinkers, particularly Galen, came to be adopted by Christianity. Once admitted within the Church's fold, their teachings became part of the established dogma. Orthodoxy substituted for observation, inhibiting learning. The number of lives lost is incalcuable, but dissent through evidence was perilous. Even the Greeks, Zimmer reminds us, considered dismembering cadavers distasteful. Real medicine was thus kept in check for centuries.
While Protestantism overthrew many dogmas, medicine remained a restrained science. The issue of the "soul", where it resided and how it functioned, remained an enigma. The stomach, liver and heart were all candidates for the home of the "soul". The brain was viewed as a "useless mass of grey porridge". Zimmer's illuminating study depicts the revolution Willis wrought in explaining the brain's central role. He learned to dissect the brain, which decays faster than other organs, and initiated explanations of the nervous system. His illustrator was none other than Christopher Wren, famous Restoration architect. Together, they demonstrated the brain's arterial and nerve arrangement in what became known as the Circle of Willis - the entwined network of signal systems and energy resources. The collaboration was published as "The Anatomy of the Brain", the founding document of the science of neurology.
Willis established what Zimmer describes as the "four pillars of neurology". The first of these is the interaction of the body through the nerves to the brain. Second, the body's activities can be mapped in particular areas in the brain. Stimulation and response thus become predictable - showing the brain is structured, not merely an incohate melange of "grey porridge". Third, Willis and his followers demonstrated the similar structure of the brains of all animals. Tests showed clearly the body-brain interaction is common to all creatures. Finally, abnormal behaviour and many illnesses can be chemically treated. Although Zimmer describes today's world as "awash in brain drugs", benefits can be derived through proper therapy.
Although Zimmer covers a wealth of material, from the ancient Greeks through modern times, you aren't overwhelmed by this history. With an accessible prose style, he explains how growing knowledge of the body led to a new science. He communicates his own enthusiasm effortlessly, drawing the reader into the story. Each chapter is prefaced by an illustration of the material - all drawn from Wren's depictions. The only lack in these graphics is a modern diagram of the brain's anatomy. His concluding chapter on modern brain mapping details brain areas reflecting particular functions and emotions. The brain may be divided physcially, but the neural network is a highly integrated structure. Zimmer has produced a compelling study of the medical and the metaphysical. [stephen a. haines - Ottawa, Canada]
