Galen (129—c. 216 CE)

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(129c. 216 CE)

Galen (Aelius or Iulius Galenus of Pergamum), a doctor and philosopher, was the son of a rich architect. Born in modern-day Bergama in western Turkey, he was introduced as a student to all the main philosophical theories of classical antiquity. On his own admission, this led him only into a confusion from which he was rescued by considering mathematics, which henceforth provided him with a paradigm for understanding truth and falsehood. From 145, following the appearance of the healing god Asclepius to his father in a dream, he turned to medicine. He sat at the feet of medical teachers in Pergamum, Smyrna, and Alexandria, as part of what is the longest recorded medical education from the ancient world. In 157 he returned to Pergamum as doctor to the gladiators of the high priest, but in 162 he traveled to Rome, the imperial capital. There he quickly established a reputation as a doctor, anatomist, and philosopher, not always to the delight of his many competitors. In 166 he left Rome hurriedly but was recalled in 168 by Emperor Marcus Aurelius to join him and his brother on campaign in northern Italy. After his return to Rome in 169, he seems to have spent the rest of his life in Italy as a physician to the emperor's household although he made at least one visit to Pergamum. The traditional date for his death, c. 200, is based on an early misunderstanding of a comment, preserved by Arabic authors, that divided his life into seventeen years as a student and seventy as a doctor. A date of death around 216 fits better with the internal evidence from his many treatises and would allow him to continue writing major treatises on medicine and pharmacology well into the first decade of the third century, or even later.

Galen was an enormously prolific author, credited with more than 350 treatises on subjects ranging from attic comedy to vivisection, and from logic to pharmacology. Roughly half of these survive today, in whole or in part, mainly in his native Greek but also in Arabic, Hebrew, Persian, and medieval Latin versions. These translations are of great importance, particularly when the originals have been lost, for they frequently deal with philosophical issues that seem to have held little interest for the Byzantine. New discoveries of previously unknown treatises can be expected as major libraries in the Muslim world are opened to scholars and more works of medieval Arabic and Jewish philosophy are published. The recent recovery of new fragments in Arabic of the lost On Scientific Discovery suggests that a complete copy of the work Galen thought his greatest contribution to philosophy may eventually be found.

Galen's interest in philosophy can be followed throughout his life, from his very early On Medical Experience to his last work, On My Own Opinions. He regarded philosophy as essential to the proper practice of medicine: The best doctor was also a philosopher, whether or not he realized it. Conversely, a knowledge of medicine was valuable for philosophers, a conjunction Galen traced back to Plato whose notions of the body in the Timaeus Galen derived from a (unhistorical) friendship with Hippocrates. In turn, Galen visualized Hippocrates as a Platonic philosopher, a claim that contributed to the growing dominance of Hippocrates as the symbol of the medical profession.

Fundamental to medicine was logic, both for structuring accurate diagnosis and for distinguishing between various degrees of certainty. Some suppositions could be proved to be true, others shown to be false, others were merely plausible and could be adopted only provisionally. Still others, such as the nature of god or the eternity of world, were incapable of proof or refutation and were best left to idle sophists. But Galen often muddled these important distinctions, either by treating the merely plausible as if it were true or by choosing as obvious and universally agreed bases for discussion facts or ideas that themselves were disputed by some of his opponents.

Galen's formal logic, on which he wrote several books, is impressive in its rigor and clarity. The Arabs' attribution to him of the discovery of the fourth syllogism may be right, or it may simply reflect Galen's extension of earlier debates about argument. Throughout his writings he stressed the importance of accuracy and clarity of expression, to avoid confusion, and to allow discussion with those offering different points of view. Ambiguity, on which he wrote an extant tract, was harmful to medicine as well as philosophy, and a sound training in logic he considered necessary for everyone. His demands for a mathematical precision in debate are not, however, fully borne out by his own practice, and his overwhelming powers of rhetoric often obscure his unscrupulous representation of the illogicality of his opponents.

His philosophy and his medicine reinforced each other. Where empirical observation was not enough by itself, logic and understanding of the theories of other philosophers could bridge the gap. Conversely, the facts of medical life exemplified and justified the cosmological and psychological doctrines of philosophers. His discussions of the value of empiricism in relation to understanding the causes of disease, one of the goals of the true doctor, show an awareness of the epistemological difficulties involved and an understanding that an experienced practitioner might reach the correct conclusion without having to go through the necessary chain of causation. He might also be a swifter and safer option than a callow youth, no matter how brilliant the youth's reasoning abilities. Galen's entire approach was eclectic, rejecting the dogmatism of the philosophical schools of his own day in favor of the "twin legs" of reason and experience.

Galen's medicine was based on an Aristotelian physics combined with a Platonic psychology. His universe, made up of the four Aristotelian elements in various combinations or mixtures, had been overseen by a purposeful Creator, or Nature, and worked along the interconnected principles favored by the Aristotelians and Stoics. His explanations for the working of drugs, for instance, involved Aristotelian language and concepts. He was convinced that each part of the body had been designed teleologically, for a particular purpose, and any alteration or imbalance in its basic elements, qualities, or humors resulted in illness. Galen's defense of teleology, as evinced in the human hand and in the elephant's trunk, is arguably superior to that of Aristotle's, and his exposition of what he termed the "natural faculties" is far from the simplistic presentation familiar from later denunciations of Galenism.

Whereas he believed strongly in the existence of the soul, he refused to be drawn to any definitive statement about what the essence of the soul was. The Aristotelian and Stoic notions of an undivided controlling power within the body he vigorously rejected as being inconsistent with the facts of anatomy. His systematic dissections of a variety of animals convinced him that there were three almost independent systems within the body corresponding to the three parts of Plato's soul, as described in the Republic and Timaeus : the brain and nerves, concerned with thought and sensation; the heart and arteries, responsible for life and energy; and the veins and liver (a more precise rendering of Plato's belly ), responsible for nutrition and growth. Galen never proclaimed a strict parallelism between the three systems, which was achieved only by later followers such as Avicenna and Averroes, and he devoted much more space to the first two than to the third. This lack of systematization was the result both of his enormous fecundity of ideas and his methods of composition, for most of his books were originally oral presentations, taken down by trained shorthand writers, and not carefully crafted treatises written at leisure. Not surprisingly, they are often repetitive and leave many knots untied.

The heart, for Galen, was the source of natural heat, and the place where a small amount of venous blood, mixed with air, was transformed into vigorous arterial blood. His repetition of the earlier experiments of Erasistratus (c. 304250 BCE) proved convincingly that the arteries contained blood and not pneuma alone, as Erasistratus had argued. But his vitalist predilections convinced him that the movement of arterial blood was not the result of any quasi-mechanical motion of the heart but brought about by the forcible contraction of the arteries controlled by natural powers within their thick coats. Just as most venous blood remained within the veins until it was absorbed as nutriment or excreted, so most arterial blood remained within the arteries. A tiny portion was transformed in the rete mirabile, a vascular plexus at the base of the skull (not found in humans but in some animals Galen dissected), to become psychic pneuma, which was refined still more in the networks of the brain to act as the means of transmission of sensation and the commands of the brain. Contrary to Aristotle and the Stoics, he could find no evidence for the heart as the seat of sensation and thought, especially since he could trace its nerves back to an origin in the innermost cavities of the brain. Galen's experimental dissections of the spinal cord in animals are among the most impressive ever performed, combining a precision of dissection with a careful planning and elucidation of what was to be achieved, and were not superseded until the mid-sixteenth century.

Galen's anatomical conclusions he believed far too important to be left entirely to doctors. In two of his longest treatises, On the Usefulness of Parts and On the Opinions of Hippocrates and Plato, he explained the consequences of his discoveries in Aristotelian and Platonic terms, respectively. Similarly, his comments on the Timaeus stressed the truth of many of Plato's observations and suggested that he must have gained his anatomical knowledge from the great Hippocrates himself. Plato was his favorite philosopher: Galen's writings are permeated with Platonic phraseology, and he wrote summaries of the Timaeus and other Platonic dialogues that are partially extant in Arabic.

A man of austere moralityGalen claimed to have read the Golden Words of Pythagoras nightlyhe wrote extensively on ethics. He advocated a self-control brought about by an extensive philosophical training although he acknowledged that this might be doubly difficult for those who had been badly trained or whose psychic genetic makeup predisposed them to evil. He advocated a very strong interaction between body and soul, for just as overeating and drinking or pleasurable and painful sensations have an obvious effect on behavior, so, in turn, anger or grief can lead to physical illness and even death. Galen contrasts his own equanimity at the loss of most of his library in a fire with his mother's shocking irascibility and with the timorousness of a patient who worried himself to death after dreaming that he had replaced Atlas as the upholder of the world. Doctor and philosopher should cooperate in the search for health and wholeness.

Anatomy also helped to resolve some philosophical disputes about intentionality. Some actions, Galen showed, were under the direct control of the brain via the nerves and muscles; others were "natural," the result of our genetic makeup, and beyond rational control; others were more complex, such as speech, which required both the will and the modification of "natural" patterns of breathing. Others, such as winking and blinking, appeared to indicate the coexistence of voluntary and involuntary activity in the same organ whereas others, such as a penile erection, he explained by other notions such as sympathy. Only laughter defeated his attempts at explanation. Throughout, Galen sought to use his medical experience to illuminate contemporary philosophical debate, just as he used philosophical debates on physics or causation to explain his decisions as a practitioner.

Contemporary reactions to his philosophy were mixed. A sect of Christians attempted to recast their Christianity to take account of his logical objections to miracles, but others were less polite. Skeptics objected to his reliance on sensory data, and the Aristotelian Alexander of Aphrodisias thought him a great doctor but a poor philosopher, whose profession in On My Own Opinions of agnosticism about many philosophical questions was a confession of failure. But his views on creation and some of his Platonic commentaries were cited with respect in the fifth century, and the Christian philosopher Nemesius of Emesa built his Christian anthropology largely on Galen's discoveries. Although much of his philosophy had disappeared in Greek by 1000, the Arabs drew heavily on his work. New fragments of his ethics recovered from Spanish Jewish writers of the twelfth and thirteenth centuries show how much they valued his approach to morality. Renaissance biographers were equally impressed, some even viewing his life as exemplifying the cardinal virtuesa perspective hardly shared by modern scholars. Others hotly debated whether he had become a Christian at the end of his life or not. But after the sixteenth century, Galenic philosophy, like his medicine, was abandoned, not to be studied again in considerable detail until the 1970s.

See also Alexander of Aphrodisias; Aristotle; Ethics; Hippocrates and the Hippocratic Corpus; Logic, History of; Nemesius of Emesa; Philosophy of Medicine; Philosophy of Science, History of; Plato; Pythagoras and Pythagoreanism; Stoicism.



DeLacy, Phillip H., ed. On the Opinions of Hippocrates and Plato/Galen. Berlin, Akademie-Verlag. 3 vols. 19781984.

Kühn, Karl Gottlob. Claudii Galeni Opera Omnia, Leipzig: Knobloch. 20 vols. in 22. 18211832. The standard edition of the Greek Galen.

Kollesch, Jutta, and Diethard Nickel, "Bibliographia Galeniana: Die Beiträge des 20. Jahrhunderts zur Galenforschung." In Aufstieg und Niedergang der römischen Welt, Teil II: Principat. Band 37, 2, edited by Wolfgang Haase and Hildegard Temporini. Berlin: De Gruyter, 1994, p. 13511420, 20632070.

May, Margaret T., trans. Galen on the Usefulness of Parts of the Body. 2 vols. Ithaca, Cornell University Press, 1968.

Muhaqqiq, Mahdi, ed. Kitab al-Shukuk 'ala Jalinus l-Muhammad ibn Zakariya al-Razi, Tehran, Mu'assasah. 1993. New fragments of On Scientific Discovery.

Nutton, Vivian, ed. Galen, On My Own Opinions. Berlin: Akademie Verlag, 1999. A list of texts not included in this edition can be found in Vivan Nutton, ed., "The Unknown Galen," Bulletin of the Institute of Classical Studies, Supp. 77, 2002.

A good selection of philosophical oriented texts is available in English in Peter N. Singer, Galen. Selected Works, Oxford: Oxford University Press, 1997.


Barnes, Jonathan. "Galen on Logic and Therapy." In Galen's Method of Healing: Proceedings of the 1982 Galen Symposium, edited by Fridolf Kudlien and Richard J. Durling. Leiden, NY: Brill, 1991, p. 50102.

Frede, Michael. Essays in Ancient Philosophy. Oxford: Clarendon Press, 1987.

Hankinson, R. James. "Galen and the Best of All Possible Worlds." Classical Quarterly 39 (1989): 206227.

Hankinson, R. James. Cause and Explanation in Ancient Greek Thought. Oxford: Clarendon Press, 1998.

Hankinson, R. James, ed. The Cambridge Companion to Galen. Cambridge, U.K.: Cambridge University Press, forthcoming.

Lloyd, Geoffrey E. R. "Theories and Practices of Demonstration in Galen." In Rationality in Greek Thought, edited by Michael Frede and Gisela Striker. Oxford: Clarendon Press, 1996, p. 255277.

Moraux, Paul. Der Aristotelismus bei den Griechen. Vol. 2. Berlin: De Gruyter, 1984.

Nutton, Vivian. Ancient Medicine. London: Routledge, 2004, p. 216247.

Rescher, Nicholas. Galen and the Syllogism: An Examination of the Thesis that Galen Originated the Fourth Figure of the Syllogism in the Light of New Data from Arabic Sources, Including an Arabic Text Edition and Annotated Translation of Ibn al-Sal ah's treatise on the Fourth Figure of the Categorical Syllogism. Pittsburgh, PA: University of Pittsburgh Press.

Smith, Wesley D. The Hippocratic Tradition. Ithaca, NY: Cornell University Press, 1979.

Temkin, Owsei. Galenism, Rise and Decline of a Medical Philosophy. Ithaca, NY: Cornell University Press, 1973.

von Staden, Heinrich. "Body, Soul, and Nerves: Epicurus, Herophilus, Erasistratus, the Stoics, and Galen." In Psyche and Soma: Physicians and Metaphysicians on the Mind-Body Problem from Antiquity to Enlightenment, edited by John P. Wright and Paul Potter. Oxford: Clarendon Press, 2000.

Zonta, Mauro. Un Interprete ebreo della Filosofia di Galeno: gli scritti filosofici di Galeno nell'opera di Shem Tob ibn Falaquera. Turin: Zamorani, 1995.

Vivian Nutton (2005)