There are two distinct periods in the history of Medieval Medicine. The first concerns the early centuries, from the sixth to the ninth, and is occupied mainly with the contributions to medicine made by those who were still in touch with the old Greek writers; while the second represents the early Renaissance, when the knowledge of the Greek writers was gradually filtering back again, sometimes through the uncertain channel of the Arabic. Both periods contain contributions to medicine that are well worthy of consideration, and nearly always the writings that have been preserved for us demonstrate the fact that men were thinking for themselves as well as studying the Greek writers, and were making observations and garnering significant personal experience. The later Middle Ages particularly present material in this regard of far greater interest than was presumed to exist until comparatively recent historical studies were completed. The real history of medicine in the Middle Ages--that is, of scientific medicine--is eclipsed by the story of popular medicine. So much has been said of the medical superstitions, many of which were rather striking, that comparatively little space has been left for the serious medical science and practice of the time, which contain many extremely interesting details. It is true that after the Crusades mummy was a favourite pharmacon, sometimes even in the hands of regular physicians; and _Usnea_, the moss from the skulls of the bodies of criminals that had been hanged and exposed in chains, was declared by many to be a sovereign remedy for many different ills; but it must not be forgotten that both of these substances continued to be used long after the medieval period, mummy even down to the middle of the eighteenth century, and Usnea almost as late. Indeed, it is probable that the seventeenth and eighteenth centuries present many more absurdities in therapeutics than do the later centuries of the Middle Ages. In this, as in so many other regards, the modern use of the adjective medieval has been symbolic of ignorance of the time rather than representative of realities in history.