that the minds of medical men were hampered by accepted doctrines. 

 One of the first of these dogmas was founded on the fact that, while in 

 the sacred Scriptures minute attention is given to precautions against 

 leprosy and skin diseases, no measures are prescribed against pest. 

 Yet most disastrous epidemics are recorded in the Old Testament. 



By the word pest is understood not only bubonic plague, but the 

 different epidemic diseases, whatever they may have been, that were 

 formerly included under that term. In their application to this group 

 of maladies the various docrines of etiology had a most important 

 bearing on etiology. The history is preserved in a great number of 

 documents, many of them obscure and quaint, but all interesting as 

 showing the gradual development of public sanitation. From an 

 etiological standpoint the history of public hygiene in its relation to 

 epidemiology is divided into four periods, during all of which widely 

 diverse views of causation of epidemic disease were held, the state of 

 knowledge in each successive epoch advancing nearer the truth. First 

 came a chaotic period up to the time of Hippocrates, secondly the cen- 

 turies that intervened from the time Hippocrates set forth his views 

 of etiology to the middle of the sixteenth century, when Fracastoro, 

 basing his observations on the epidemic prevalence of syphilis that 

 extended throughout Europe, announced a theory of contagion. 

 Then followed an interval lasting until the evidence of a living con- 

 tagion gained credence. Lastly came the time when specific germs 

 were found to be the cause of epidemic disease. The last era, how- 

 ever, brings the history of quarantine to such a recent time as to be 

 outside the scope of the present writing. 



The word plague as well as pest was given by ancient medical writers 

 to any epidemic disease that wrought an extensive destruction of life. 

 Oalen, for example, used the word in this sense. History is replete 

 with epidemics. Instances of ancient prevalences are the disastrous 

 disease, recorded in II Kings, causing the destruction of the Assyrian 

 army; the plague of Athens, described by Thucydides; the great 

 pestilence in the reign of Marcus Aurelius, that extended over almost 

 the whole of Europe, and the plague of Justinian, descriptions of 

 which are given by Procopius and Evagrius. The plague of Justinian 

 lasted for fifty years and has a decided interest in connection with the 

 present subject, having been introduced in all probability largely by 

 sea. It began at Pelusium, in Egypt, 542 A. D. After spreading 

 through Egypt it appeared the next year at Constantinople. In sub- 

 sequent years it advanced over the entire Roman world, making its 

 initial appearance in seaboard towns and radiating inland. Frequent 

 epidemics occurred in succeeding centuries, one of the most important 

 of which was the great cycle of epidemics in the fourteenth century, 

 which has been given the name of the ' ' black death. " Throughout all 



