Why does a person exhibit qualities within a crowd that they do not display when they are alone and acting on their own? Why, under the influence of the masses, do their cognitive abilities diminish, do they have extreme emotional reactions, or do they show selflessness and self-sacrifice? This is what Freud considers the essential question of a psychology of crowds. And he is not concerned with it only because "mass phenomena" begin to dominate in the society of his time, nor because in the mature period of his thinking he aspires to shape a broader anthropological approach beyond the pathology of the individual patient. For him, individual psychology cannot exist separate from the influence of others; it ultimately emerged from the psychology of the masses. Taking a detour, therefore, into the theories of his time regarding the formation of the mass, Freud will argue that its formation is primarily due to libidinal relationships. He will continue his audacious forays into prehistory, where he will encounter the formation of the archaic mass and the primitive horde, in order to explain the emotional relationships between individuals, as well as with the leader, starting from the murder of the archaic father.
Concepts such as identification, as well as a new level of the Ego, the ideal Ego, will be used to clarify the mystery of the influence that leaders exert on the individuals of the mass. The same goes for the concept of hypnosis, to which Freud returns, in order to reaffirm its privileged but also enigmatic relationships with the unconscious.