Although the above early epidemics cannot be identified with the bubonic plague, there is nevertheless excellent evidence of the existence of this disease in remote antiquity. The first undoubted testimony on this point is that furnished by Rufus of Ephesus, who lived in the first century of the Christian era. The writings of this author are no longer extant, but they are quoted by Oribasius, the physician and friend of Julian the Apostate, who lived in the fourth century. The writings of Oribasius were discovered in the Vatican Library and were published early in this century by Cardinal Mai. In the forty-fourth “Book of Oribasius” occurs the extract taken from Rufus of Ephesus, from which it appears that “the so-called pestilential buboes are all fatal and have a very acute course, especially when observed in Libya, Egypt and in Syria. Dionysius mentions it. Dioscorides and Posidonius have described it at length in their treatise upon the plague which prevailed during their time in Libya.” The description which then follows of the buboes and of the disease is an exact counterpart of the present plague. The writings of the authors quoted by Rufus are no longer extant, but one thing is certain, and that is that the Dionysius referred to lived not later than 300 years before Christ. The other two physicians lived in Alexandria contemporaneous with the birth of Christ. It may, therefore, be considered as an established fact that the plague existed in Egypt, Libya and Syria as early as 300 years before Christ. This is of especial interest in view of the recent discovery by Koch of an endemic plague focus in British Uganda and German Kisiba, at the headwaters of the Nile. Whether it ever invaded European territory prior to the sixth century is unknown. The great plague of Justinian which broke out in 542, Anno Domini, appeared first in Egypt, and from thence it spread east and west throughout the known world and persisted for more than a half century. So unknown was the plague in Europe at that time that the physicians of Constantinople considered it a new disease. Procopius, who was an eye-witness of the plague at Constantinople, states that the daily mortality in that city was at times over 10,000.