Galen Synthesizes Ancient Medical Knowledge Summary

  • Last updated on November 11, 2022

Galen synthesized ancient medical knowledge, combining preexisting medical knowledge with his own ideas in writings that dominated European medical thinking for some fifteen hundred years after his death.

Summary of Event

Galen, a Greek subject of the Roman Empire, was born in 129 c.e. in Pergamon, a city in Asia Minor considered to be second only to Alexandria as a great center of learning in the Roman Empire. After studying philosophy in Pergamon and serving as a surgeon to gladiators, he moved to Alexandria to study anatomy. In 169, Galen took a position as the personal physician of the Roman emperor Marcus Aurelius, and his eminence as a medical teacher was widely recognized. At Rome, he had access to the imperial library’s vast collection of medical writings from the farthest reaches of the empire. Combining his own observations and research with this great store of medical knowledge, Galen’s writings, more than any other source, influenced Western medical thinking for approximately fifteen hundred years after his death. Galen Hippocrates (c. 460-c. 370 b.c.e.)

Galen wrote down for posterity the accomplishments of the great early figures of medicine. Hippocrates, the father of medicine, is largely known to the modern world through the writings of Galen. The Hippocratics, followers of Hippocrates, built on the scientific foundation laid by Hippocrates. Their collections of observations and research were kept alive by Galen for subsequent generations. If not for Galen, most of the Hippocratic literature would have perished, and the modern world would know nothing about the work of the great Alexandrian anatomists of the fourth and third centuries b.c.e. such as Herophilus and Erasistratus who pioneered work on the nervous and circulatory systems. Galen’s seventeen-volume medical treatise De usu partium corporis humani (written between 165 and 175 c.e.; On the Usefulness of the Parts of the Body, 1968) summarized the medical knowledge of his day and preserved the medical knowledge of his predecessors.

Galen, in his book De naturalibus facultatibus (c. late second century c.e.; On the Natural Faculties, 1916) expanded on Hippocrates’ theory of the four humors, or bodily wet substances: black bile, yellow bile, blood, and phlegm. According to Galen, in addition to the physiological abnormalities caused by imbalances of these humors, psychological differences would also result. Furthermore, overabundances of different humors were linked with distinct temperaments (personality predispositions). Thus, excess black bile could result in sadness (melancholic temperament); too much yellow bile in excitability and being easily angered (choleric temperament); excess phlegm in sluggishness and introversion (phlegmatic temperament); and too much blood in cheerfulness and extroversion (sanguine temperament). The influence of this theory is still seen in the contemporary use of words such as sanguine and phlegmatic and in expressions such as, “Are you in a good humor today?” Even the red-striped barber’s pole was originally the sign of an individual who would drain blood to improve the health of others.


(Library of Congress)

Although he was not a Christian, Galen was strongly opposed to atheistic, materialistic explanations of nature and the human body. He believed that nature reflects a divine design and so does the body. God breathes life into nature, and according to Galen, the divine life-giving principle in humans is called pneuma (from the Greek “breeze”). Three adaptations of pneuma give the following attributes of living creatures: the natural spirit produces growth; the vital spirit causes locomotion; and the animal (from the Latin term anima, meaning soul) spirit is what makes intellectual functioning possible. Galen’s studies of anatomy and physiology were often conducted to determine the flow of these spirits throughout the human body. Pneuma theory dominated Western medical thinking until well into the eighteenth century.

Galen not only wrote on the impact of physiological factors on mental activities but also concluded that thinking could affect physiology. This is illustrated in an incident in which Galen was treating a female patient. Galen noticed that when the name of Pylades, a male dancer, was mentioned, the patient’s heart rate became irregular. When the names of other male dancers were mentioned, there were no effects on her pulse. Galen concluded from this that the patient was “in love” with the dancer and that thinking can lead to physiological consequences. Thus, the first clear description of a psychosomatic (mind-body) relationship can be said to originate with Galen.

Dealing with psychological problems was also a concern of Galen. He wrote of the importance of counsel and education in treating psychological problems. Therapy, according to Galen, should involve a mature, unbiased older person, confronting clients whose passions, such as anger and jealousy, were thought to be primarily responsible for their psychological problems. Such advice by Galen illustrates an ancient idea of psychotherapy. Other advice by Galen on psychological matters is contained in his books De propriorum animi cujusque affectuum dignotione et curatione and De cujuslibet animi peccatorum dignotione atque medela (c. late second century c.e.; translated together as On the Passions and Errors of the Soul, 1963).


Galen’s ideas dominated Western medical thinking from his era until the Renaissance. His strongly theistic attitudes were embraced by the Christian thinkers who began to prevail over the affairs of the later Roman Empire. Early Christian writers from the second to the fourth centuries c.e., such as Tertullian, Lactantius, Nemesius, and Gregory of Nyssa, integrated Galen’s ideas into many of their works. Unfortunately, Galen’s numerous medical treatises (more than four hundred) were often summarized and distorted by other, inferior, writers, and the Galenism that dominated Western medical thinking from the Dark Ages through medieval times was often far removed from Galen’s original writings. Nevertheless, Galen’s influence was so profound that even many Renaissance texts began with an acknowledgment to the great contributions of Galen, particularly his emphasis on observation and experimentation.

The profound impact of Galen on subsequent Western thinking is demonstrated most clearly in examining the influence of his theories of pneuma and humors. The three adaptations of pneuma can be seen to be influential in the writings of the great theologian Saint Thomas Aquinas (1224/1225-1274) in his description of the faculties (or powers) of the soul. The philosophy of René Descartes (1596-1650) is often considered to mark the beginning of the modern period of philosophy. He has also been called the father of physiology for his descriptions of the workings of the human body. These descriptions contained something new, the demonstration of the circulation of the blood by William Harvey (1578-1657), and something old, the animal spirits from Galen’s writings.

The old theory of humors, expanded on by Galen, resurfaced in the twentieth century in the work of two noted psychologists. Ivan Petrovich Pavlov (1849-1936), whose work on classical conditioning is one of the greatest contributions to the history of psychology, accepted Galen’s classification of temperaments and even extended the theory to dogs, the primary subjects of his research. The distinguished British psychologist Hans Eysenck presented a personality theory in 1964 that incorporated some of Galen’s ideas. Indeed, modern research on introversion and extroversion can be seen to have its philosophical antecedents in Galen’s theory of humors.

The work of Galen united philosophy with science and rationalism (major source of knowledge is reason) with empiricism (major source of knowledge is experience). His writings are a connection to ancient thinkers and yet his influence on twentieth century theories can be seen. Galen was a practical man dedicated toward discovering the facts of medicine, and his influence is likely to continue to be found in future medical practices.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Eysenck, Hans J. “Principles and Methods of Personality Description, Classification, and Diagnosis.” British Journal of Psychology 55 (1964): 284-294. A description of twentieth century personality theory in consideration of Galen’s theory of humors.
  • citation-type="booksimple"

    xlink:type="simple">Galen. On the Natural Faculties. Translated by Arthur John Brock. New York: Putnam, 1916. Considered Galen’s most important psychological work.
  • citation-type="booksimple"

    xlink:type="simple">Galen. On the Passions and Errors of the Soul. Translated by Paul W. Harkins. Columbus: Ohio State University Press, 1963. This work shows Galen’s interest in psychology.
  • citation-type="booksimple"

    xlink:type="simple">Galen. On the Usefulness of the Parts of the Body. Translated by M. T. May. Ithaca, N.Y.: Cornell University Press, 1968. A seventeen-volume work containing Galen’s most extensive description of the ancient anatomical literature.
  • citation-type="booksimple"

    xlink:type="simple">García-Ballester, Luis. Galen and Galenism: Theory and Medical Practice from Antiquity to the European Renaissance. Burlington, Vt.: Ashgate, 2002. An examination of ancient medicine, focusing on Galen and his influence. Bibliography and index.
  • citation-type="booksimple"

    xlink:type="simple">Nutton, Vivian, ed. The Unknown Galen. London: Institute of Classical Studies, University of London, 2002. A collection of papers presented at a joint symposium on Galen held in 1999.
  • citation-type="booksimple"

    xlink:type="simple">Robinson, Daniel N. An Intellectual History of Psychology. 3d ed. Madison: University of Wisconsin Press, 1995. A brief description of Galen is presented, emphasizing his scientific thinking.
  • citation-type="booksimple"

    xlink:type="simple">Viney, Wayne. A History of Psychology: Ideas and Context. Boston: Allyn & Bacon, 1993. Contains a summarization of Galen’s life with unique (such as his influence on Pavlov) emphasis on his contributions to psychology.
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