Claudius Galenus (Galen) – Greek physician and philosopher (129 AD- approx. 216 AD) was the ultimate authority on anything related to medicine for more than 1,500 years. He synthetized the works of his predecessors and promoted the Hippocratean theory of humors. As a physician he carried on the Aristotelian doctrine that in nature, form follows function. Therefore, it is vital to study organs and body parts in order to understand their functions.

He was considered a brilliant anatomist, though he could perform only animal dissections (work on human cadavers was forbidden by Roman law). He was a prolific author and his works were disseminated in Greek, Arabic, and Latin. His teachings were studied and followed without serious criticism for centuries.

It was not until Galen’s translator, Andreas Vesalius, published De humani corporis fabrica in 1543 that his fifteen centuries of supremacy in anatomy ended and Vesalius became the anatomist to follow.