Concurrently, however, there were other physicians and laymen who saw in contagion the principal factor responsible for the rise and spread of epidemic disease. This view was presented in a systematic form in 1546 by GirolamoFracastoro (1478-1533) in his treatise De contagione, contagiosis morbis et eorum curatione (On Contagion, Contagious Diseases and their treatment). This book is one of the great landmarks in the evolution of a scientific theory of communicable disease. Fracastoro has been mentioned several times in connection with specific diseases, and it is evident that his work on contagion was based on wide and practical study of plague, typhus fever, syphilis, and other epidemic diseases. His treatise comprises three books: the first presents his theory of contagion, the second discusses various contagious diseases, and the third deals with their cures.