For thirteen centuries his name and influence dominated the medical profession in Europe, Asia, and Africa; and this influence, under the name of Galenism, was paramount in the eighteenth century, notwithstanding the discovery of the circulation of the blood and other great advances in science. Galen collected and co-ordinated all the medical knowledge which previous physicians and anatomists had acquired. He was no mere collector of, or compiler of other men’s works; but he enriched previous acquirements by his own observation, and was in every way a man greatly in advance of his time. “A great and profound spirit,” says Daremberg, “he was philosopher as well as physician, realising the aspiration of Hippocrates when he said that the physician who should be also a philosopher must be the equal of the gods. A dialectician like Aristotle, a psychologist like Plato, who glorified his work by his genius for interpreting nature and life, his position as philosopher would have been beside those men, if his devotion to medicine had not called him to another sphere of intellectual activity.” Nevertheless, Galen did in fact occupy an exalted position in the history of philosophy, not only in the West, but amongst the Arabians. His encyclopædic knowledge, his spirit of observation, and his influence on the thought of the middle ages, compel a comparison with Aristotle. It was thus that the vast body of medical material collected by the various sects and schools was analysed by the penetrating genius of Galen, whose philosophical and scientific mind was able to extract the good and permanent from the worthless and ephemeral material, which encumbered the literature of the healing art. He fell under the domination of none of the schools, though in one sense he may be said to have leaned towards the Dogmatists, “for his method was to reduce all his knowledge, as acquired by the observation of facts, to general theoretical principles.”[497] He endeavoured to draw the student of medicine back to Hippocrates, of whom he was an admirer and expounder. The labours of Galen had the effect of destroying the vitality of the old medical sects; they became merged in his system, and left off wrangling amongst themselves to imitate the new master who had arisen. A crowd of new writers found in the works of Galen abundant material for their industry.
Partly in consequence of this jealousy, and partly from the fact that in A.D. 167 a pestilence broke out in Rome, he left the city privately, and returned to his native country.
Galen, as a profound anatomist and physiologist, recognised final causes, a purpose in all parts of the bodies which he dissected; and it is, as Whewell points out,[498] impossible for a really great anatomist to do other than recognise these. He cannot doubt that the nerves run along the limbs, in order that they may convey the impulses of the will to the muscles: he cannot doubt that the muscles are attached to the bones, in order that they move and support them.
The development of this conviction, that there is a purpose in the parts of animals of a function to which every organ is subservient, greatly contributed to the progress of physiology; it compelled men to work till they had discovered what the purpose is. Galen declared that it is easy to say with some impotent pretenders that Nature has worked to no purpose. He has an enthusiastic scorn of the folly of atheism.[499] “Try,” he says, “if you can imagine a shoe made with half the skill which appears in the skin of the foot.” Somebody had expressed a desire for some structure of the human body over that which Nature has provided. “See,” he exclaims, “what brutishness there is in this wish. But if I were to spend more words on such cattle, reasonable men might blame me for desecrating my work, which I regard as a religious hymn in honour of the Creator. True piety does not consist in immolating hecatombs, or in bearing a thousand delicious perfumes in His honour, but in recognising and loudly proclaiming His wisdom, almighty power, love and goodness. The Father of universal nature has proved His goodness in wisely providing for the happiness of all His creatures, in giving to each that which is most really useful for them. Let us celebrate Him then by our hymns and chants! He has shown His infinite wisdom in choosing the best means for contriving His beneficent ends; He has given proof of His omnipotence in creating everything perfectly conformable to its destination.”
Anatomy must have reached a high standard before Galen’s time, as we learn from his corrections of the mistakes and defects of his predecessors. He remarks that some anatomists have made one muscle into two, from its having two heads; that they have overlooked some of the muscles in the face of an ape in consequence of not skinning the animal with their own hands. This shows that the anatomists before Galen’s time had a tolerably complete knowledge of the science. But Galen greatly advanced it. He observes that the skeleton may be compared to the pole of a tent or the walls of a house. His knowledge of the action of the muscles was anatomically and mechanically correct. His discoveries and descriptions even of the very minute parts of the muscular system are highly praised by modern anatomists.[500]
He knew the necessity of the nerve supply to the muscle, and that the brain originated the consequent motion of a muscle so supplied, and proved the fact experimentally by cutting through some of the nerves and so paralysing the part.[501] Where the origin of the nerve is, there, he said, it is admitted by all physicians and philosophers is the seat of the soul. This, he adds, is in the brain and not in the heart. The principles of voluntary motion were well understood, therefore, by Galen, and he must have possessed “clear mechanical views of what the tensions of collections of strings could do, and an exact practical acquaintance with the muscular cordage which exists in the animal frame:—in short, in this as in other instances of real advance in science, there must have been clear ideas and real facts, unity of thought and extent of observation, brought into contact.”[502]
He observed that although a ligature on the inguinal or axillary artery causes the pulse to cease in the leg or in the arm, the operation is not permanently injurious, and that even the carotid arteries may be tied with impunity. He corrects the error of those who, in tying the carotids, omitted to separate the contiguous nerves, and then wrongly concluded that the consequent loss of voice was due to compression of the arteries.
Galen was the first and greatest authority on the pulse, if not our sole authority; for all subsequent writers simply transferred his teaching on this subject bodily to their own works.[503]
Briefly it was as follows: “The pulse consists of four parts, of a diastole and a systole, with two intervals of rest, one after the diastole before the systole, the other after the systole before the diastole.”[504]
His therapeutics were based on these two principles:—“1. That disease is something contrary to nature, and is to be overcome by that which is contrary to the disease itself; and 2. That nature is to be preserved by that which has relation with nature.”[505]