The affective temperament is a specific constitutional disposition, a dimensional construct, and only the extremes can be considered abnormal in statistical and perhaps in a clinical sense. For the definition of the affective temperaments, Akiskal proposed some criteria. Briefly, this is the concept of “fundamental states” of Kraepelin, with the employ of the classical term of “temperament”. The spectrum is used to refer to the broad range of such manifestations of a disorder, from core symptoms to temperamental traits. In DSM-III, the expression “Major Depression” replaced the terms of melancholia and endogenous. The reference to the endogenous has been abandoned because its theoretical implications.