is perhaps as a rule too weak to be noticed by a self-controlled, unemotional man. But if we want an example of this influence at its strongest, we need but remember how difficult it is for an individual to resist the contagion of collective feeling.[117] On public occasions the common mood, whether of joy or sorrow, is often communicated even to those who were originally possessed by the opposite feeling. So powerful is the infection of great excitement that—according to M. Féré—even a perfectly sober man who takes part in a drinking bout may often be tempted to join in the antics of his drunken comrades in a sort of second-hand intoxication, “drunkenness by induction.”[118] In the great mental epidemics of the Middle Ages this kind of contagion operated with more fatal results than ever before or afterwards. But even in modern times a popular street riot may often show us something of the same phenomenon. The great tumult in London in 1886 afforded, it is said, a good opportunity of observing how people who had originally maintained an indifferent attitude were gradually carried away by the general excitement, even to the extent of joining in the outrages.[119] In this instance the contagious effect of expressional movements was undoubtedly facilitated by their connection with so primary an impulse as that of rapine and destruction. But the case is the same with all the activities which appear as the outward manifestations of our strongest feeling-states. They all consist of instinctive actions with which every one is well familiar from his own experience. It is therefore natural that anger, hate, or love may be communicated almost automatically from an individual to masses, and from masses to individuals.