Contributions to medicine

Galen contributed a substantial amount to the Hippocratic understanding of pathology. Under Hippocrates' bodily humors theory, differences in human moods come as a consequence of imbalances in one of the four bodily fluids: blood, yellow bile, black bile, and phlegm. Galen promoted this theory and the typology of human temperaments. In Galen's view, an imbalance of each humor corresponded with a particular human temperament (blood—sanguine, black bile—melancholic, yellow bile—choleric, and phlegm—phlegmatic). Thus, individuals with sanguine temperaments are extroverted and social; choleric people have energy, passion, and charisma; melancholics are creative, kind, and considerate; and phlegmatic temperaments are characterized by dependability, kindness, and affection.

Galen's principal interest was in human anatomy, but Roman law had prohibited the dissection of human cadavers since about 150 BC. Because of this restriction, Galen performed anatomical dissections on living (vivisection) and dead animals, mostly focusing on primates.^[6] This work was useful because Galen believed that the anatomical structures of these animals closely mirrored those of humans. Galen clarified the anatomy of the trachea and was the first to demonstrate that the larynx generates the voice.

Contemporary scholarship

Galenic scholarship remains an intense and vibrant field, following renewed interest in his work, dating from the German encyclopedia Realencyclopädie der Classischen Altertumswissenschaft.

Copies of his works translated by Robert M. Green are held at the National Library of Medicine in Bethesda, Maryland.

In 2018, the University of Basel discovered that a mysterious Greek papyrus with mirror writing on both sides, which was at the collection of Basilius Amerbach, a professor of jurisprudence at the University of Basel in the 16th century, is an unknown medical document of Galen or an unknown commentary on his work. The medical text describes the phenomenon of ‘hysterical apnea’.^[

Published work

Galen may have produced more work than any author in antiquity, rivaling the quantity of work issued from Augustine of Hippo So profuse was Galen's output that the surviving texts represent nearly half of all the extant literature from ancient Greece. It has been reported that Galen employed twenty scribes to write down his words. Galen may have written as many as 500 treatises amounting to some 10 million words.^] Although his surviving works amount to some 3 million words, this is thought to represent less than a third of his complete writings. In AD 191, a fire in the Temple of Peace destroyed many of his works, in particular treatises on philosophy.

Because Galen's works were not translated into Latin in the ancient period, and because of the collapse of the Roman Empire in the West, the study of Galen, along with the Greek medical tradition as a whole, went into decline in Western Europe during the Early Middle Ages, when very few Latin scholars could read Greek. However, in general, Galen and the ancient Greek medical tradition continued to be studied and followed in the Eastern Roman Empire, commonly known as the Byzantine Empire. All of the extant Greek manuscripts of Galen were copied by Byzantine scholars. In the Abbasid period (after AD 750) Arab Muslims began to be interested in Greek scientific and medical texts for the first time, and had some of Galen's texts translated into Arabic, often by Syrian Christian scholars (see below). As a result, some texts of Galen exist only in Arabic translation, while others exist only in medieval Latin translations of the Arabic. In some cases scholars have even attempted to translate from the Latin or Arabic back into Greek where the original is lost. For some of the ancient sources, such as Herophilus, Galen's account of their work is all that survives.