'...The individual in the relations which have already been mentioned to his parents and to his brothers and sisters to the person he is in love with to his friend and to his physician comes under the influence of only a single person or of a very small number of persons each one of whom has become enormously important to him. Now in speaking of Social or Group Psychology it has become usual to leave these relations on one side and to isolate as the subject of inquiry the influencing of an individual by a large number of people simultaneously people with whom he is connected by something though otherwise they may in many respects be strangers to him. Group Psychology is therefore concerned with the individual man as a member of a race of a nation of a caste of a profession of an institution or as a component part of a crowd of people who have been organised into a group at some particular time for some definite purpose...