ABSTRACT
A simple gathering of persons should be strictly differentiated from collectivities of persons inspired by the same idea, agitated by the same feelings, pursuing the same goal. Such collectivities representing temporary and occasional relations of people, as distinct from society at large, seemingly turn themselves into a single enormous personality, feeling and acting as a unified whole. When such a collectivity is already formed, when it is unified under the influence of one common psychic impulse, then the main leading role in its further actions falls to suggestion and mutual suggestion. A common manifestation of social contagion is the so called herd instinct, one of the elements of which is the automatic imitation characteristic of the whole animal world but displayed more obviously in animals living a social life. In the human, the herd instinct, or automatic imitation, is particularly displayed where one has a joint life, owing to certain conditions which are sometimes completely external.
