11 



ORIGIN OF THE DOCTRINE OF CONTAGION. 



The credit of having created the doctrine that pest is contagious by 

 contact with the sick and their effects is chiefly due to Jacobo della 

 Torre, known also by the name of Jacopo da Forli, from the name of 

 a city in central Italy, where he was born in the second half of the 

 fourteenth century. Contagion had been referred to obscurely and 

 timidly from Aristotle down, but now the idea took a practical form. 

 The old notion was that f omites were a sort of tinder that caught from 

 the air an infection existing independently of the sick. Many writers, 

 including Galen, believed there was an extreme degree of atmospheric 

 pollution in the vicinity of the sick, rendering such neighborhoods 

 dangerous, but this was considered a primary cause of the illness rather 

 than a direct emanation from the sick. 



Della Torre's doctrines were not accepted by the various schools of 

 medicine and were for a time absolutely forgotten. Fracastoro pro- 

 claimed the same theories at a later period, when they were better 

 received, and to him is generally given the honor of announcing the 

 theory of contagion. Jacobo della Torre advised the magistrates of 

 his native town to remove outside the city all persons affected with 

 pest and to isolate them, as well as all persons who had been with 

 them. The authorities were warned against delay, for it was avowed 

 that every precaution would be futile should the disease become dif- 

 fuse throughout, the city. In his recommendations no mention is made 

 of purification, but he asserted his disagreement from the accepted 

 belief in the stellar origin of the infective principle. Delia Torre's 

 disciple, Michele Savonarola, attained greater eminence than his mas- 

 ter, and so far vindicated the honor of his school as to declare that even 

 persons in good health may transport the pestilential virus to distant 

 places, and that those who are not brought in association with the vic- 

 tims of pest or with pest-bearing things escape the disease. But 

 Savonarola did not fully indorse the teachings of his preceptor. He 

 could not shake off a belief in astrology and admitted that the origin 

 of pest resided in a disorder of the air generated in consequence of 

 planetary contact. 



Giovanni da Concorrezzo, toward the second half of the fourteenth 

 century, was so profoundly convinced that pest came exclusively from 

 universal aerial pollution that he denounced as useless every precaution 

 to check the advances of the disease and affirmed that all measures 

 designed to avert contagion are inefficacious. 



At this period, when the world had about decided that in epidemics 

 sanitation was not worth while, three observing men lent their influ- 

 ence to broader views and thus gave a potent stimulus to the doctrine 

 of contagion. These writers were Alessandro Benedetti, Marsilio 

 Ficino, and Gerolamo Fracastoro. 



