Willow bark of the willow tree have been mentioned in ancient texts from Assyria, Sumer and Egypt as a remedy for aches and fever, and in Ancient Greece the physician Hippocrates wrote about its medicinal properties in the fifth century BC. Native Americans across the Americas relied on it as a staple of their medical treatments. It provides temporary pain relief. Salicin is metabolized into salicylic acid in the human body, and is a precursor of aspirin. In 1763, its medicinal properties were observed by the Reverend Edward Stone in England. He notified the Royal Society, which published his findings. The
Hippocrates widely considered to be the "Father of Medicine". His contributions revolutionized the practice of medicine; but after his death the advancement stalled. So revered was Hippocrates that his teachings were largely taken as too great to be improved upon and no significant advancements of his methods were made for a long time. The centuries after Hippocrates' death were marked as much by retrograde movement as by further advancement. For instance, "after the Hippocratic period, the practice of taking clinical case-histories died out," according to Fielding Garrison. After Hippocrates, the next significant physician was Galen, a Greek who lived from AD