Why does a person exhibit traits within a crowd that they do not display when acting alone? Why, under the influence of the mass, do their mental abilities decline, exhibit extreme emotional reactions, or show selflessness and self-denial? This is considered by Freud to be the essential question of a psychology of the masses.

And he does not engage with it only because “mass phenomena” begin to dominate the society of his time, nor because, in the mature period of his thinking, he aspires to form a broader anthropological approach, beyond the pathology of the individual patient. For him, individual psychology cannot exist detached from the influence of others; it ultimately emerged from the psychology of the mass.

Taking a stroll, then, through the theories of his time regarding the formation of the mass, Freud will argue that the formation is primarily due to libidinal relations. He will continue, thus, his daring excursions into prehistory, where he encounters the formation of the primal mass and the primitive horde, in order to explain the emotional relationships of individuals with one another, but also with the leader, starting from the murder of the primal father.

Concepts such as identification, as well as a new stage of the Ego, the ideal Ego, will be used to elucidate the mystery of the influence that leaders exert on individuals in the mass. The same goes for the concept of hypnosis, to which Freud returns to reaffirm its privileged but also enigmatic relationships with the unconscious.

[Excerpt from the text on the back cover of the edition]