In contrast to the hypothesis of different nosological entities of so-called “endogenous” psychoses (e.g. schizophrenia, manic-depressive psychosis) the model of unitary psychosis has been discussed in controversial terms. The starting point of those discussions was the concept of a unitary nosological and pathogenic entity which may be traced back to Joseph Guislain and has inspired the work of Wilhelm Griesinger, who further elaborated the concept of Unitary Psychosis ("Einheitspsychose"). Griesinger, who was also influenced by Zeller's idea of the unified human soul or character (“Gemüt”), argued that madness was the consequence of a single disease of the brain. In comparison to that the Unitary Psychoses concept of Janzarik focuses not on the nosological position but on the pathogenetic mechanisms of endogenous psychoses (e.g. structural-dynamic coherence model). Recent co-morbidity studies as well as trans-nosographical analyses have called classical categorical diagnosing more and more in question. The development of dimensional diagnostics, as an alternative to categorical diagnostic systems led to a renaissance of the unitary psychosis ideas. Such dimensional diagnostics do not focus any longer on artificial disease constructs and their nosological position but on single psychopathological phenomena, on their plasticity during the pathological process, and their constellations of conditions. The main task of Dimensional Diagnostics, as introduced here in this paper, is not only the accurate description and explanation of psychopathological phenomena and processes but has to include also the understanding of the suffering person's deficiencies and resources.