when the libidinal cathexis has been withdrawn from the object, it is directed, as we know, to the ego, while at the same time the object is introjected into the ego. The ego must now bear all the consequences of this process
Abraham's central thesis: in melancholia, libido withdrawn from the lost object is redirected to the ego via introjection, exposing the ego to the full ambivalence of the libidinal impulses.
, Selected Papers on Psychoanalysis, 1927thesis