Willow bark preparations became a standard part of the "materia medica" of Western medicine beginning at least with the Greek physician Hippocrates in the fifth century BCE; he recommended chewing on willow bark to relieve pain or fever and drinking tea made from it to relieve pain during childbirth. The Roman encyclopedist Celsus, in his "De Medicina" of ca. 30 AD, suggested willow leaf extract to treat the four signs of inflammation: redness, heat, swelling and pain. Willow treatments also appeared in Dioscorides's "De Materia Medica", and Pliny the Elder's "Natural History". By the time of Galen around the year 200 C.E., willow bark was commonly used throughout the Roman world and later after the Arab–Byzantine wars passed on to the Arab world as a small part of a large, growing botanical pharmacopeia.