Pathology has made us acquainted with a great number of states in which the boundary lines between the ego and the external world become uncertain or in which they are actually drawn incorrectly. There are cases in which parts of a person's own body, even portions of his own mental life - his perceptions, thoughts and feelings -, appear alien to him and as not belonging to his ego; there are other cases in which he ascribes to the external world things that clearly originate in his own ego and that ought to be acknowledged by it.
Sigmund FreudIn mourning it is the world which has become poor and empty; in melancholia it is the ego itself.
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