Pedanius Dioscorides
In medicine, doctors still refer to the Hippocratic oath, instituted by Hippocrates, regarded as foremost in laying the foundations of medicine as a science. Galen built on Hippocrates' theory of the four humours, and his writings became the foundation of medicine in Europe and the Middle East for centuries. The physicians Herophilos and Paulus Aegineta were pioneers in the study of anatomy, while Pedanius Dioscorides wrote an extensive treatise on the practice of pharmacology.