The first part of this article deals with Tellenbachs conception of Melancholia. The typical premorbial personality structure, Typus Melancholicus, is seen to be dominated by 'Ordentlichkeit', which is a rigid and exclusive fixation on order in the fundamental areas of life. The pathogenetic development of this personality structure occurs via certain premelancholical basic situations, in which the two mechanisme, 'Inkludentio' (limitation of self to narrow boundaries) and 'Remanentio' (failure to self-realisation) are brought into effect and produce disorder to replace the previous order. The discontinuous transition to psychosis is only made if the particular endon is capable of qualitative pathological change, either idiokinetic or endotropic; this Tellenbach terms endokinesis. These three elements, namely Typus Melancholicus, 'Inkludentio- and Remanentio'-initiating situations and endokinesis are essential to the development of full blown Melancholia. This fact is shown to have certain therapeutic consequences. The second part of this article confronts this model for investigation of depression with a clinical case, which is interpreted using Tellenbachs model. We feel convinced that this author has much to offer in the understanding of certain patients with endogenous depression, and that his conceptions add valuable new insights to the classical psychodynamical theories on Melancholia.