272 PSYCHOLOGY AND PREACHING
conditions in Mexico; but after the excitement incident to the great war seized upon the public mind of America the Mexican situation, although gravely accentuated and im periling important interests of this country, attracted little at tention and caused hardly a thrill of emotion. One cannot reasonably expect a great wave of religious feeling to sweep a community during a period of deep and pervasive political excitement. Why is this ? Perhaps it is due, in part, to the fact that people at any given time have only a certain amount of energy. At any rate, whatever may be the ultimate ex planation, the human mind normally tends to centralize and unify its activity ; some interest comes to be for a time dom inant, and around it both the intellectual and emotional activ ities are organized.
4. These excitements spread along lines of mental ho mogeneity, of common interest and frequent contact. This is an obvious and inevitable consequence of the fact before pointed out that they result partly from a similar response of like-minded people to the same stimuli ; and partly from the communication of ideas and feelings from one to another.
III. What are the general conditions which are favour able to the occurrence of mental epidemics?
I. A large uncultured population. By an uncultured population is meant people who are ignorant, uneducated; people who have had but a limited and monotonous experi ence, and people of low mental organization. Among these classes an excitement of any kind which strongly stimulates the instincts will spread rapidly. As this large number are swept into the psychical vortex the suction becomes very powerful. Minds of a higher order are drawn in. As the swirl of the engulfing current thus widens, it looses from their moorings minds that are yet more securely anchored in reason ; and so goes on spreading until the steadiest intellects become dizzy and normal thinking and acting become all but impossible. If there were but a small proportion of people of inferior intelligence the current could not attain sufficient force to disturb the mental equilibrium of the leaders. To
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