A History of Magic and Experimental Science, Volume 1 (of 2) / During the First Thirteen Centuries of Our Era

by Lynn Thorndike

Aristotle had held that the heart was the seat of the sensitive soul[637] and the source of nervous action, “while the brain was of secondary importance, being the coldest part of the body, devoid of blood, and having for its chief or only function to cool the heart.” Galen attacked this theory by showing experimentally that “all the nerves originated in the brain, either directly or by means of the spinal cord, which he thought to be a conducting organ merely, not a center.” “A thousand times,” he says, “I have demonstrated by dissection that the cords in the heart called nerves by Aristotle are not nerves and have no connection with nerves.” He found that sensation and movement were stopped and even the voice and breathing were affected by injuries to the brain, and that an injury to one side of the brain affected the opposite side of the body. His public demonstration by dissection, performed in the presence of various philosophers and medical men, of the connection between the brain and voice and respiration and the commentaries which he immediately afterwards dictated on this point were so convincing, he tells us fifteen years later, that no one has ventured openly to dispute them.[638] His “experimental investigation of the spinal cord by sections at different levels and by half sections was still more remarkable.”[639] Galen opposed these experimental proofs to such unscientific arguments on the part of the Stoic philosopher, Chrysippus, and others, as that the heart must be the chief organ because it is in the center of the body, or because one lays one’s hand on one’s heart to indicate oneself, or because the lips are moved in a certain way in saying “I” (ἐγώ).[640] Another noteworthy experiment by Galen was that in which, by binding up a section of the femoral artery he proved that the arteries contain blood and not air or spiritus as had been generally supposed.[641] He failed, however, to perform any experiments with the pulmonary veins, and so the notion persisted that these conveyed “spirit” and not blood from the lungs to the heart.[642]

Did Galen ever dissect human bodies?

It has usually been stated that Galen never dissected the human body and that his inferences by analogy from his dissection of animals involved him in serious error concerning human anatomy and physiology. Certainly he speaks as if opportunities to secure human cadavers or even skeletons were rare.[643] He mentions, however, the possibility of obtaining the bodies of criminals condemned to death or cast to beasts in the arena, or the corpses of robbers which lie unburied in the mountains, or the bodies of infants exposed by their parents.[644] It is not sufficient, he states in another passage,[645] to read books about human bones; one should have them before one’s eyes. Alexandria is the best place for the student to go to see actual exhibitions of this sort made by the teachers.[646] But even if one cannot go there, one may be able to procure human bones for oneself, as Galen did from a skeleton which had been washed out of a grave by a flooded stream and from the corpse of a robber slain in the mountains. If one cannot get to see a human skeleton by these means or some other, he should dissect monkeys and apes.

Dissection of animals.

Indeed Galen advises the student to dissect apes in any case, in order to prepare himself for intelligent dissection of the human body, should he ever have the opportunity. From lack of such previous experience the doctors with the army of Marcus Aurelius, who dissected the body of a dead German, learned nothing except the position of the entrails. Galen at any rate dissected a great many animals. Tiny animals and insects he let alone, for the microscope was not yet discovered, but besides apes and quadrupeds he cut up many reptiles, mice, weasels, birds, and fish.[647] He also gives an amusing account of the medical men at Rome gathering to observe the dissection of an elephant in order to discover whether the heart had one or two vertices and two or three ventricles. Galen assured them beforehand that it would be found similar to the heart of any other breathing animal. This particular dissection was not, however, performed exclusively in the interests of science, since it was scarcely accomplished when the heart was carried off, not to a scientific museum, but by the imperial cooks to their master’s table.[648] Galen sometimes dissected animals the moment he killed them. Thus he observed that the lungs always sensibly shrank from the diaphragm in a dying animal, whether he killed it by suffocation in water, or strangling with a noose, or severing the spinal medulla near the first vertebrae, or cutting the large arteries or veins.[649]

Surgical operations.

Surgical operations and medical practice were a third way of learning the human anatomy, and Galen complains of the carelessness of those physicians and surgeons who do not take pains to observe it before performing an operation or cure. He himself had had one case where the human heart was laid bare and yet the patient recovered.[650] As a young practitioner before he came to Rome Galen worked out so successful a method of treating wounds of the sinews that the care of the health of the gladiators in his native city of Pergamum was entrusted to him by several successive pontifices[651] and he hardly lost a life. In the same passage he again speaks contemptuously of the doctors in the war with the Germans who were allowed to cut open the bodies of the barbarians but learned no more thereby than a cook would. When Galen came from Pergamum to Rome he found the professions of physicians and surgeons distinct and left cases to the latter which he before had attended to himself.[652] We may note finally that he invented a new form of surgical knife.[653]

Galen’s argument from design.

In Galen’s opinion the study of anatomy was important for the philosopher as well as for the physician. An understanding of the use of the parts of the body is helpful to the doctor, he says, but much more so to “the philosopher of medicine who strives to obtain knowledge of all nature.”[654] In the De usu partium[655] he came to the conclusion that in the structure of any animal we have the mark of a wise workman or demiurge, and of a celestial mind; and that “the investigation of the use of the parts of the body lays the foundation of a truly scientific theology which is much greater and more precious than all medicine,” and which reveals the divinity more clearly than even the Eleusinian mysteries or Samothracian orgies. Thus Galen adopts the argument from design for the existence of God. The modern doctrine of evolution is of course subversive of his premise that the parts of the body are so well constructed for and marvelously adapted to their functions that nothing better is possible, and consequently of his conclusion that this necessitates a divine maker and planner.

In the treatise De foetuum formatione Galen displays a similar inclination but more tentatively and timidly. He thinks that the human body attests the wisdom and power of its maker,[656] whom he wishes the philosophers would reveal to him more clearly and tell him “whether he is some wise and powerful god.”[657] The process of the formation of the child in the womb, the complex human muscular system, the human tongue alone, seem to him so wonderful that he will not subscribe to the Epicurean denial of any all-ruling providence.[658] He thinks that nature alone cannot show such wisdom. He has, however, sought vainly from philosopher after philosopher for a satisfactory demonstration of the existence of God, and is by no means certain himself.[659]