I recently read Carl Zimmer’s book, Soul Made Flesh: The Discovery of the Brain – and How It Changed the World, and I found it fascinating. (It has only added to my intellectual crush on the thinkers of the early Enlightenment. *sigh*) It is, essentially, the story of how the study of neurology came into being. But it is also the tale of how the brain came to light, because before neurology could come into existence, the brain had to be “discovered” as more than just a useless tapioca-like substance. And so, it is a book about the history of the brain, as humans have understood it over time.
One of the interesting things is just how much of the book is also about medical and philosophical understandings of the heart. The title of “Soul Made Flesh” is very descriptive, (as one might expect,) because the whole journey of understanding started in an attempt to understand the soul. Where was it located? How did it work? What was it that made humans so special, above the other animals? What drove our moral actions? Naturally, it started out as a philosophical quest.
As you might imagine, the philosophical descriptions of the soul, its location, and how it worked were nicely explained, logically argued, and based on very little in the way of fact. In trying to localize the soul, the philosophers were trying to base their arguments on human anatomy, and so they also made up what today seem like extremely fanciful interpretations of how the imagined bodily systems all worked together. There were lots of descriptions of little spirits and humors running around to different locations of the body to influence different human functions. Eventually, the heart was settled upon as the home of the soul, as well as the home of thought.
Fortunately for us, in the 1600s, people, particularly young intellectuals, early natural philosophers, if you will, began to find fault with their Greek-based anatomy classes, and started to notice that what was actually being revealed of the human body in the dissection theater didn’t always tally with what was in the books. And so the revolution began, and the real story started.
A young man named Thomas Willis in England had intended to be a clergyman. The only problem was, his college years corresponded with the overthrow of the monarchy, which rather took the Church of England with it, so it wasn’t such a great time to be a royalist man of the cloth. So he became a physician instead, and fell in with that group of natural philosophers who would later become the Royal Society. Who better than a devoutly religious ex-ministerial-candidate turned physician, with a bunch of highly inquisitive friends interested in everything and quite willing to perform any experiment imaginable, anatomical to mechanical, to discover the true workings of the brain?
Willis was one of those not satisfied with the way anatomy stood. When William Harvey, a maverick anatomist who prefered to base his theories on observation, rather than tradition, proposed the idea that blood flowed in a continuous loop around the body, and was not in fact, replenished from the outside, he revolutionized all ideas about the heart. Harvey had no use for the brain, but the heart was now simply an organ. Willis was free to find a new home for the soul.
The book’s descriptions of the experiments Willis and his Royal Society friends thought of to test their hypotheses are amazing. When his friends helped him discover how to preserve brains as specimens, he and his assistants were then free to dissect them accurately and painstakingly. (Not to mention that along the way they discovered oxygen, redefined the respiratory system, and performed the first successful blood transfusion, as well.) No more assumptions based on the anatomy of cows, no more need to scrape away outer tissue as it became less stable during decomposition, thereby obscuring the true ways the brain’s structures connected. He was able to follow the branching pathways of nerves, to develop a whole new theory of the different kinds of thought, voluntary and involuntary. He tied the different kinds of thought to the different main areas of the brain, in ways that still hold true.
It’s breathtaking to think of living in a time when so many new discoveries were being made, though I have to admit it’s likely they didn’t realize it themselves at the time. But the truth is that Willis’s descriptions of the brain, and the nervous system that he discovered, along with the accompanying illustrations by Christopher Wren, remained quite accurate and relevant into the 20th century. There’s so much more to this story than what I’m able to encapsulate here, and I can’t recommend this book enough to anyone who has any interest in the brain, neurology, and/or philosophy of the soul. To see this history laid out so clearly is breathtaking. It’s like being able to witness the discovery of the very basis of our modern world, and yet, at the same time, reminds us of what there is still left to discover. The brain is still an amazingly unknown territory.