In order to study the difference between depression, mourning, and melancholia one must be aware of intermediate states; e.g., pathological mourning. Mourning is normal and is considered a healthy reaction of ego restitution in people who have reached the genital stage of development. In depression or melancholia, since the death instinct is the dominant element, pathologic process precludes ego restitution and the death instinct could be so strong as to lead to suicide. In melancholia the loss of the love object is not related to reality, but depends on the regression of the patient to primitive, archaic, and infantile libidinal and ego stages.