Once started on these lines, I occupied myself specially with the subject, and arrived at the surprising result, that the Venereal Disease of the XVth. Century owed its terrible characteristics solely and entirely to the contemporary exanthematic-typhoïdal _Genius Epidemicus_, which made itself known in the South of Europe by petechial fevers and by the _Sudor Anglicus_ (English Sweating-fever) in the North. I concluded further that the disease was not epidemic at all, merely liable to arise under epidemic influence; and must consequently have been already extant before the arrival of the said _Genius Epidemicus_. Time and circumstances compelled me to remain satisfied provisionally with this general conclusion, and only after I had fixed my abode permanently at Halle, could I resume my earlier investigations. Yet again these were interrupted, partly by my work on the Diseases of the Skin for the Dictionary of Surgery edited by Prof. Blasius, partly by my Habilitation (formal entry on the Staff) at the University of that place, to which I had been repeatedly invited after the unexpected death of the late Dr. Baumgarten-Crusius. Eventually I was enabled to devote the greater part of my leisure hours to this subject, one which in the meantime was never quite lost sight of. I began to sift and arrange the material I found accumulated, but in a short time I convinced myself that in its treatment I had to strike out a different road from that followed hitherto, if I ever intended on my own account to reach important results; and I felt it would be impossible to complete the whole Survey in a single moderate-sized volume. Consequently I proceeded to limit myself to the enquiry whether or no Venereal disease had been extant in Ancient times, and it is this investigation that I now publish as a first Part of the History of Venereal disease.