288 POPULAR SCIENCE MONTHLY. 



association can have little place, or, to express it physiologically, the 

 unusual excitement in the lower centers of the brain accompanying 

 excessive emotion may not only find expression in muscular movements, 

 but may also exercise an inhibitory or paralyzing effect upon the higher 

 centers, resulting in a kind of hypnotic condition. Neither is it diffi- 

 cult to understand the presence of this excessive emotion during mental 

 epidemics or during any purely social movements, when we remember 

 that war itself is the great original social movement, which even in 

 this age always takes the form of a mental epidemic called the war 

 spirit. The emotional effect of the mere physical congregation of a 

 large number of men, the emotion increasing with the size of the assem- 

 blage, is known to all. 



As we glance now at a few of the typical mental epidemics of history, 

 we shall notice the ever-recurring presence of some or all of the mental 

 and moral traits that I have pointed out. For illustrations of these 

 phenomena we may turn indifferently to ancient, medieval or modern 

 history. They abound at every period. 



Very good examples may be found in Hecker's 'Epidemics of the 

 Middle Ages.' In the Crusades, particularly in the Children's Cru- 

 sades, we may observe all the mental, moral and physical peculiarities 

 that have been mentioned. In the anti-Semitic mania, we see in its 

 history of criminal horror the dehumanizing effects of the epidemic 

 and the moral reversion which takes place under the influence of 

 social excitement. The peculiar physical phenomena which have been 

 referred to as characterizing epidemic excitement are best illustrated 

 in the dancing manias of the Middle Ages and in the religious revival. 

 Although epidemic 'revivals' have occurred in all countries, some of 

 the best illustrations are seen in America in its early history and to 

 some extent at the present day. At the time of the elder Edwards, 

 revivals were accompanied by fainting, falling, tremor and numbness. 

 In the Kentucky revivals the meetings, called camp meetings, were held 

 in the open air. The interest in them spread in true epidemic form. 

 At the height of the excitement, as many as 20,000 people, men, women 

 and children, were gathered in a single camp at one time. Dr. David- 

 son, who writes a history of this revival, says that "the laborer quitted 

 his task, age snatched his crutch, youth forgot his pastime, the plough 

 was left in the furrow, business of all kinds was suspended, bold hunters 

 and sober matrons, young men, maidens and little children flocked to 

 the common center of attraction." The emotional tension was very 

 great. A boy perhaps would spring to his feet and begin to rave, or 

 some over-excited person would utter a piercing shriek, or a cry of 

 triumph, and this would be the signal for a general hysterical outbreak, 

 accompanied by many remarkable physical symptoms. Of these the 

 most common were falling in convulsive spasms, jerking, dancing, 



