G.J.C. Lokhorst. Review of Julius Rocca, Galen on the Brain: Anatomical Knowledge and Physiological Speculation in the Second Century AD (Leiden/Boston: Brill, 2003). Journal for the History of the Neurosciences, 2003. ISSN 0964-704X.
Julius Rocca, Galen on the Brain: Anatomical Knowledge and Physiological Speculation in the Second Century AD (Studies in Ancient Medicine, Vol. 26). Leiden/Boston: Brill, 2003. ISBN 90-04-12512-4. EUR 85.00 / US $ 99.00.
Galen's (AD 129-c.210) writings on the brain and its functions are the most impressive contributions to neuroscience from classical Antiquity that are still in existence. They dominated the field until the sixteenth century and did not become obsolete until the seventeenth century. In his Galen on the Brain, Julius Rocca offers a detailed, integrated and critical account of Galen's anatomy and physiology of the brain, setting it within the cultural and intellectual context of its era. He begins by assessing Galen's debt to his predecessors in medicine (primarily Hippocrates, Herophilus, "the father of neuroscience", and Erasistratus) and philosophy (primarily Plato and Aristotle). While doing so, he pays much attention to Galen's arguments in favor of encephalocentrism, the view that the brain, not the heart, is the leading part (command center) of the body. After this, there is a long account of Galen's work on the anatomy of the brain. Unlike Herophilus and Erasistratus, Galen did not perform dissection and vivisection on human subjects, but only on animals. His studies were largely based on the ox, but he also used apes, sheep, pigs and goats. He extrapolated his findings to the human brain.
Galen's account of the brain has been described as "one of the best examples of the apogee of Greek anatomical science," and Rocca shows in detail how much truth there is in this statement. Galen described very carefully which procedures one should follow when dissecting the brain, and the picture of the gross anatomy of the brain which he presented is still very recognizable. It would still be hard to improve on it without using a microscope. In the course of his detailed description of Galen's findings, Rocca also addresses the longest-standing puzzle in the secondary literature about Galen's neuroanatomy: does his description of a channel between the third and fourth ventricles refer to the aqueduct of Sylvius or did Galen describe some other, artificial passage? Daremberg (1841) and May (1968) advocated the latter view, whereas several other authors have uncritically assumed that Galen must have been referring to the Sylvian aqueduct. Rocca argues in a quite convincing way that the latter view is indeed correct. There is no reason to assume that Galen did not refer to the aqueduct. Rocca is able to reach this conclusion because he uses a method which is more or less unique in the field of ancient medicine. Most authors rely solely on texts, but Rocca does not confine himself to philological methods: he continually tries to verify Galen's statements by means of actual dissections of the ox's brain. This is highly appropriate in the case at hand, for puzzles such as the one we have mentioned cannot be solved in any other way.
After describing Galen's neuroanatomical work, Rocca discusses his neurophysiological views. These views are, in a sense, much less impressive than his neuroanatomy. In order to understand the working of the brain one should at least have some knowledge of chemistry, but this science did not yet exist in Galen's time. Galen had a pneumatic conception of the working of the brain. He believed that the air contains a rarefied component called pneuma (spirit), which enters the ventricles through the nose and the retiform plexus at the base of the brain (a structure which, in reality, does not exist in man). He thought that this pneuma flowed from the anterior ventricles to the fourth ventricle, in the meanwhile undergoing some form of purification or digestion, with the result that it was transformed into a subtle psychic pneuma (later called "animal spirits"). He maintained that this psychic pneuma, whose flow was regulated by the vermis of the cerebellum, was somehow the main factor in the functioning of the brain. The resulting theory left, of course, much to be desired. Rocca appropriately calls the last section of his description of Galen's physiology "The limits of Galenic pneumatic physiology." Yet Galen could hardly have done better. It was not until the discovery of electricity in the eighteenth century that people came in a position to frame alternative hypotheses.
In conclusion: Rocca's book is a very thorough and impressive study of one of the most important subjects in the history of the neurosciences. It will probably remain the definitive reference for a long time and can heartily be recommended to everyone interested in the early development of neuroscience.
Daremberg, C. (1841), Exposition des connaissances de Galien sur l'anatomie, la physiologie et la pathologie du système nerveux, Paris.
May, M.T. (1968), Galen: On the Usefulness of the Parts of the Body (2 vols.), Ithaca, N.Y.: Cornell University Press.
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