Galen, father of systematic medicine. An essay on the evolution of modern medicine and cardiology.

Galen (129-217) was the ultimate authority on all medical subjects for 15 centuries. His anatomical/physiological concepts remained unchallenged until well into the 17th century. He wrote over 600 treatises, of which less than one-third exist today. The Galenic corpus is stupendous in magnitude; the index of word-entries in it contains 1300 pages. Galen's errors attracted later attention, but we should balance the merits and faults in his work because both exerted profound influences on the advancement of medicine and cardiology. Galen admonished us to embrace truth as identified by experiment, warning that everyone's writings must be corroborated by directly interrogating Nature. His experimental methods' mastery is demonstrated in his researches, spanning every specialty. In his life-sustaining schema, the venous, arterial, and nervous systems, with the liver, heart, and brain as their respective centers, were separate, each distributing through the body one of three pneumata: respectively, the natural, the vital, and the animal spirits. He saw blood carried both within the venous and arterial systems, which communicated by invisible "anastomoses," but circulation eluded him. The "divine Galen's" writings, however, contributed to Harvey's singular ability to see mechanisms completely differently than other researchers, thinkers and experimentalists. Galen was the first physician to use the pulse as a sign of illness. Some representative study areas included embryology, neurology, myology, respiration, reproductive medicine, and urology. He improved the science and use of drugs in therapeutics. Besides his astounding reputation as scientist-author and philosopher, Galen was deemed a highly ethical clinician and brilliant diagnostician.