Aelius Galenus or Claudius Galenus (September AD 129 – 199/217; Greek: Γαληνός, Galēnos, from adjective "γαληνός", "calm"), better known as Galen of Pergamon (modern-day Bergama, Turkey), was a prominent Roman (of Greek ethnicity) physician, surgeon and philosopher. Arguably the most accomplished of all medical researchers of antiquity, Galen contributed greatly to the understanding of numerous scientific disciplines including anatomy, physiology, pathology, pharmacology, and neurology, as well as philosophy, and logic.
The son of Aelius Nicon, a wealthy architect with scholarly interests, Galen received a comprehensive education that prepared him for a successful career as a physician and philosopher. He traveled extensively, exposing himself to a wide variety of medical theories and discoveries before settling in Rome, where he served prominent members of Roman society and eventually was given the position of personal physician to several emperors.
Galen's understanding of anatomy and medicine were principally influenced by the then-current theory of humorism, as advanced by many ancient Greek physicians such as Hippocrates. His theories dominated and influenced Western medical science for nearly two millennia. His anatomical reports, based mainly on dissection of monkeys and pigs, remained uncontested until 1543, when printed descriptions and illustrations of human dissections were published in the seminal work De humani corporis fabrica by Andreas Vesalius where Galen's physiological theory was accommodated to these new observations. Galen's theory of the physiology of the circulatory system endured until 1628, when William Harvey published his treatise entitled De motu cordis, in which he established that the blood circulates with the heart acting as a pump. Medical students continued to study Galen's writings until well into the 19th century. Galen conducted many nerve ligation experiments that supported the theory, which is still believed today, that the brain controls all the motions of the muscles by means of the cranial and peripheral nervous systems.
Galen saw himself as being both a physician and a philosopher, as he wrote in his treatise entitled That the Best Physician is also a Philosopher. Galen was very interested in the debate between the rationalist and empiricist medical sects, and his use of direct observation, dissection and vivisection represents a complex middle ground between the extremes of those two viewpoints. Many of his works have been preserved and/or translated from the original Greek, although many were destroyed and some credited to him are believed to be spurious. Although there is some debate over the date of his death, he was no younger than seventy when he died.
Early life: AD 129-AD 161
Galen describes his early life in On the affections of the mind. Born in September 129 AD, his father Aelius Nicon was a wealthy patrician, an architect and builder, with eclectic interests including philosophy, mathematics, logic, astronomy, agriculture and literature. Galen describes his father as a "highly amiable, just, good and benevolent man". At that time Pergamon was a major cultural and intellectual centre, noted for its library (Eumenes II), second only to that in Alexandria and attracted both Stoic and Platonic philosophers, to whom Galen was exposed at age 14. His studies also took in each of the principal philosophical systems of the time, including Aristotelian and Epicurean. His father had planned a traditional career for Galen in philosophy or politics and took care to expose him to literary and philosophical influences. However Galen states that in around 145 AD, his father had a dream in which the god Asclepius (Aesculapius) appeared and commanded Nicon to send his son to study medicine. Again, no expense was spared, and following his earlier liberal education, at 16 he began studies at the prestigious local sanctuary or Asclepieum dedicated to Asclepius, god of medicine, as a θεραπευτής (therapeutes, or attendant) for four years. There he came under the influence of men like Aeschrion of Pergamon, Stratonicus and Satyrus. Asclepiea functioned as spas or sanitoria to which the sick would come to seek the ministrations of the priesthood. The temple at Pergamon was eagerly sought by Romans in search of a cure. It was also the haunt of notable people such as Claudius Charax the historian, Aelius Aristides the orator, Polemo the sophist, and Cuspius Rufinus the Consul.
In 148, when he was 19, his father died, leaving him independently wealthy. He then followed the advice he found in Hippocrates' teaching and travelled and studied widely including Smyrna (now Izmir), Corinth, Crete, Cilicia (now Çukurova), Cyprus and finally the great medical school of Alexandria, exposing himself to the various schools of thought in medicine. For a brief period in Hellenistic Alexandria, vivisections of human prisoners took place and were recorded in the work of Hellenistic anatomists. Galen had access to these works while in Alexandria, but his lack of citation to his predecessors leaves unclear how important they were to his study. In 157, aged 28, he returned to Pergamon as physician to the gladiators of the High Priest of Asia, one of the most influential and wealthiest men in Asia. The High Priest chose Galen over other physicians after Galen claims he eviscerated an ape and challenged other physicians to repair the damage. When they refused, Galen did the surgery himself and in doing so won himself the favor of the High Priest of Asia. Over the four years there he learnt the importance of diet, fitness, hygiene and preventive measures, as well as living anatomy, and the treatment of fractures and severe trauma, referring to their wounds as "windows into the body". Only five deaths occurred while he held the post, compared to sixty in his predecessor's time, generally ascribed to his attention to their wounds. At the same time he pursued studies in theoretical medicine and philosophy.
Later years: AD 162-AD 217
Galen went to Rome in 162 AD and made his mark as a practicing physician. His impatience brought him into conflict with other doctors and he felt menaced by them. His demonstrations there antagonized the less able and original physicians in the city. They plotted against him and he feared he might be driven away or poisoned so he left the city.
Rome then engaged in the foreign wars in 161 AD. Marcus Aurelius and his colleague Lucius Verus were in the north fighting the Marcomanni. During the fall of 169 AD when Roman troops were returning to Aquileia, the great plague broke out and the emperor summoned Galen back to Rome. He was ordered to accompany Marcus and Verus to Germany as the court physician. In the following spring Marcus was persuaded to release Galen after receiving a report that Asclepius was against the project. He was left behind to act as physician to the imperial heir Commodus. It was here in court that Galen wrote extensively on medical subjects. Ironically, Lucius Verus died in 169, and Marcus Aurelius Antoninus died in 180, both victims of the plague.
Galen was the physician to Commodus for much of the emperor's life and treated his common illnesses. According to Dio Cassius 72.14.3-4, in about 189 AD, under Commodus' reign, a pestilence occurred, the largest of which he has knowledge, in which 2,000 people died in Rome each day. It is most likely that this was the same plague that struck Rome during Marcus Aurelius' reign.
Galen became physician to Septimius Severus during his reign in Rome. Galen compliments Septimius and Caracalla on keeping a supply of drugs for their friends and mentions three cases in which they had been of use in 198 AD
The Antonine Plague
The Antonine Plague was named after Marcus Aurelius' family name of Antoninus. It was also known as the Plague of Galen and holds an important place in medicinal history because of its association with Galen. Galen had first hand knowledge of the disease. He was in Rome when it struck in 166 AD. He was also present in the winter of 168-9 during an outbreak among troops stationed at Aquileia. He had experience with the epidemic and refers to it as very long lasting and describes its symptoms and his treatment of it. Unfortunately, his references to the plague are scattered and brief. Galen was not trying to present a description of the disease so that it could be recognized in future generations; he was more interested in the treatment and physical effects of the disease. For example, in his writings about a young man afflicted with the plague, he concentrated on the treatment of internal and external ulcerations. According to Niebuhr "this pestilence must have raged with incredible fury; it carried off innumerable victims. The ancient world never recovered from the blow inflected upon it by the plague which visited it in the reign of M. Aurelius." The mortality rate of the plague was 7-10 percent; the outbreak in 165-6-168 would have caused approximately 3.5 to 5 million deaths. Otto Seek believes that over half the population of the empire perished. J. F. Gilliam believes that the Antonine plague probably caused more deaths than any other epidemic during the empire before the mid 3rd century. It is believed that the Antonine Plague was smallpox, because though his description is incomplete, Galen gave enough information to enable a firm identification of the disease.
Galen notes that the exanthema covered the victim's entire body and was usually black. The exanthem became rough and scabby where there was no ulceration. He states that those who were going to survive developed a black exanthem. According to Galen, it was black because of a remnant of blood putrefied in a fever blister that was pustular. His writings state that raised blisters were present in the Antonine plague, usually in the form of a blistery rash. Galen states that the skin rash was close to the one Thucydides described. Galen describes symptoms of the alimentary tract via a patient's diarrhea and stools. If the stool was very black, the patient died. He says that the amount of black stools varied. It depended on the severity of the intestinal lesions. He observes that in cases where the stool was not black, the black exanthum appeared. Galen describes the symptoms of fever, vomiting, fetid breath, catarrh, cough and ulceration of the larynx and trachea.
When Peripatetic philosopher Eudemus became ill with Quartan fever, Galen felt obliged to treat him "since he was my teacher and I happened to live nearby." Galen wrote: "I return to the case of Eudemus. He was thoroughly attacked by the three attacks of quartan ague, and the doctors had given him up, as it was now mid-winter."  Some Roman physicians criticized Galen for his use of the prognosis in his treatment of Eudemus. This practice conflicted with the then-current standard of care, which relied upon divination and mysticism. Galen retaliated against his detractors by defending his own methods. Garcia-Ballester quotes Galen as saying: "In order to diagnose, one must observe and reason. This was the basis of his criticism of the doctors who proceeded alogos and askeptos."  However, Eudemus warned Galen that engaging in conflict with these physicians could lead to his assassination. "Eudemus said this, and more to the same effect; he added that if they were not able to harm me by unscrupulous conduct they would proceed to attempts at poisoning. Among other things he told me that, some ten years before, a young man had come to the city and had given, like me practical demonstrations of the resources of our art; this young man was put to death by poison, together with two servants who accompanied him."
Garcia-Ballester says the following of Galen's use of prognosis: "In modern medicine, we are used to distinguishing between the diagnostic judgment (the scientific knowledge of what a patient has) and the prognostic judgment (the conjecture about what will happen to him.) Galen, like the Hippocratics, was not. For him, to understand a clinical case technically, 'to diagnose', was among other things, to know with greater or lesser certainty the outcome fore the patient, 'to prognosticate'. Prognosis, then, is one of the essential problems and most important objectives of Galenic diagnosis. Galen was concerned to distinguish it from divination or prophecy, both to improve diagnosis technically and to enhance the physician's reputation."
The 11th century Suda lexicon states that Galen died at the age of 70, therefore about the year 199. However, there is a reference in Galen's treatise "On Theriac to Piso" (which may however be spurious) to events of 204. There are also statements in Arabic sources that he died at 87, after 17 years studying medicine and 70 practicing it, therefore about 217. Nutton believes that "On Theriac to Piso" is genuine, the Arabic sources are correct and that the Suda has erroneously interpreted the 70 years of Galen's career in the Arabic tradition as referring to his whole lifespan. Boudon-Millot more or less concurs and favours a date of 216.
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 advanced this theory, creating a typology of human temperaments. An imbalance of each humor corresponded with a particular human temperament (blood-sanguine, black bile-melancholic, yellow bile-choleric, and phlegm-phlegmatic). Individuals with sanguine temperaments are extroverted and social. Choleric people have energy, passion and charisma. Melancholics are creative, kind and considerate. 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 pigs and primates. This work turned out to be particularly useful because in most cases, the anatomical structures of these animals closely mirror those of humans. Galen clarified the anatomy of the trachea and was the first to demonstrate that the larynx generates the voice. Galen may have understood the importance of artificial ventilation, because in one of his experiments he used bellows to inflate the lungs of a dead animal.
Among Galen's major contributions to medicine was his work on the circulatory system. He was the first to recognize that there were distinct differences between venous (dark) and arterial (bright) blood. Although his many anatomical experiments on animal models led him to a more complete understanding of the circulatory system, nervous system, respiratory system and other structures, his work was not without scientific inaccuracies. Galen believed that the circulatory system consisted of two separate one-way systems of distribution, rather than a single unified system of circulation. His understanding was that venous blood was generated in the liver, from where it was distributed and consumed by all organs of the body. He posited that arterial blood originated in the heart, from where it was distributed and consumed by all organs of the body. The blood was then regenerated in either the liver or the heart, completing the cycle. Galen also believed in the existence of a group of blood vessels he called the rete mirabile, near the back of the human brain. Both of these theories of the circulation of blood were later shown to be incorrect.
In his work De motu musculorum, Galen explained the difference between motor and sensory nerves, discussed the concept of muscle tone and explained the difference between agonists and antagonists.
Galen was also a highly skilled surgeon, and he performed surgical operations on human patients. Many of the procedures and techniques that he utilized would not be used again for centuries. Of particular note are procedures that Galen performed on patients' brains and eyes. In order to correct cataracts in patients, Galen performed an operation that was similar to what is performed by contemporary ophthalmologists. Using a needle-shaped instrument, Galen attempted to remove the cataract from behind the lens of the eye.
At first reluctantly, but then with increasing vigour, Galen promoted Hippocratic teaching including venesection and bloodletting, then unknown in Rome. This was sharply criticised by the Erasistrateans, who predicted dire outcomes, believing that it was not blood but pneuma that flowed in the veins. Galen however staunchly defended venesection in his three books on the subject, and in his demonstrations and public disputations.
Contributions to philosophy
Although the main focus of his work was on medicine, anatomy, and physiology, Galen also wrote about logic and philosophy. His writings were influenced by earlier Greek and Roman thinkers, including Plato, Aristotle, and the Stoics. Several schools of thought existed within the medical field during Galen's lifetime, the main two being the Empiricists and Rationalists (also called Dogmatists or Philosophers), with the Methodists being a lesser, more moderate group. The Empiricists emphasized the importance of physical practice and experimentation, or "active learning" in the medical discipline. In direct opposition to the Empiricists were the Rationalists, who valued the study of established teachings in order to create new theories in the name of medical advancements. The Methodists formed somewhat of a middle ground, as they were not as experimental as the Empiricists, nor as theoretical as the Rationalists. The Methodists mainly utilized pure observation, showing greater interest in studying the natural course of ailments than making efforts to find remedies.
Galen was highly interested in the importance of combining philosophical thought with medical practice, an idea he expressed in his brief work "That the Best Physician is also a Philosopher." He refused to be placed into one particular school of thought, instead taking aspects from each group and combining them with his original thoughts to form his own unique approach to medicine. He was a proponent of medicine as a highly interdisciplinary field that was best practiced by utilizing theory, observation, and experimentation in conjunction to yield the most complete results. This attitude was largely a result of his pluralist education, which exposed him to the four major schools of thought (Platonists, Peripatetics, Stoics, Epicureans), and encouraged him to pick and choose aspects from each to adhere to. His early education also included instruction from teachers who belonged to both the Rationalist and Empiricist sects, allowing him to learn about the merits of both schools.
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 600 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, particularly 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, Galen and the ancient Greek medical tradition generally 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 750 AD) 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.
Even in his own time, forgeries and unscrupulous editions of his work were a problem, prompting him to write On his Own Books. Forgeries in Latin, Arabic or Greek continued until the Renaissance. Some of Galen's treatises have appeared under many different titles over the years. Sources are often in obscure and difficult to access journals or repositories. Although written in Greek, by convention the works are referred to by Latin titles, and often by merely abbreviations of those. No single authoritative collection of his work exists, and controversy remains as to the authenticity of a number of works attributed to Galen. Consequently research on Galen's work is fraught with hazard.
Various attempts have been made to classify Galen's vast output. For instance Coxe (1846) lists a Prolegomena, or introductory books, followed by 7 classes of treatise embracing Physiology (28 vols.), Hygiene (12), Aetiology (19), Semeiotics (14), Pharmacy (10), Blood letting (4) and Therapeutics (17), in addition to 4 of aphorisms, and spurious works. The most complete compendium of Galen's writings, surpassing even modern projects liament (ssen3cadaver nerAbbalatning works amount to sommedtrgerectsowed bubstantiad="ormeo prb Mu For i. Although writ(narsm(12ow">