The functional importance of the ego is manifested in the fact that normally control over the approaches to motility devolves upon it. Thus in its relation to the id it is like a man on horse back, who has to hold in check the superior strength of the horse; with this difference, that the rider tries to do so with his own strength while the ego uses borrowed forces.
Sigmund FreudThe analytic psychotherapist thus has a threefold battle to wage -- in his own mind against the forces which seek to drag him down from the analytic level; outside the analysis, against opponents who dispute the importance he attaches to the sexual instinctual forces and hinder him from making use of them in his scientific technique; and inside the analysis, against his patients, who at first behave like opponents but later on reveal the overvaluation of sexual life which dominates them, and who try to make him captive to their socially untamed passion.
Sigmund Freud