In this clinical seminar, we will work on the question of differential diagnosis from the perspective of the Lacanian Orientation, focusing on the following: (i) the structural clinic organized around the signifier of the Name-of-the-Father and the binary differentiation between the clinic of neuroses and the clinic of the psychoses; (ii) Lacan’s later teaching (including the changing status of the signifier, jouissance, the symptom and the body) that leads to the articulation of the Borromean clinic and the hypothesis that, "everyone is mad, that is, delusional" (Lacan, "There are Four Discourses"); and, (iii) Jacques-Alain Miller’s conceptualization of the category of ordinary psychoses. Each seminar meeting will be organized around a reading of theoretical texts that elaborate clinical structure as well as published clinical cases that highlight and bring together the aspect of structure alongside the singularity, under transference, of each case.