Lacan develops his topical-logical model of the unconscious on the basis of the logical quadrilateral from Aristotle's Peri hermeneias. The simple but analytically revealing basic operation of this model is the so-called creative negation: a double negation which - in contrast to modern propositional logic - does not dissolve into a simple affirmation or into nothing, but results in an unforeseen phenomenon of meaning - like the determinate negation of Hegel's dialectical logic, to which it can be well approximated. The author shows that it is the unconscious thus defined and his unconventional "logic of the constitutive exception" that underlie Lacan's notion of discursive intersubjectivity, as well as his gender theory, that is, his definitions of female and male sexuated subjects from Seminar XIX and XX respectively, which only become intelligible against this background."The Logic of the Unconscious in Art" is the title because, in Hegel's sense, a work of art is understood as a kind of subject and because, like a subject, it is analysed in terms of a structurally unconscious. Of this unconscious, which is experienced in the viewer's imagination as aesthetic meaning, it is shown, among other things, that it has a peculiar temporality. In the grammar of everyday language, the so-called prospective imperfect corresponds to it. It speaks of something that seems to have been, but belongs to a dimension that neither was (despite the imperfect), nor can or will be, but is literally un-past, so that this unconscious "exists" between the work of art and the viewer in an unreal way. Using Michelangelo's Moses sculpture, Velázquez' Las meninas and Sophocles' Antigone, and thus following in the footsteps of Freud, Lacan and Hegel, the author explains this and other features of Lacan's model of subjectivity and sexuation. In doing so, he makes a genuine contribution to aesthetics and the interpretation of works of visual art and literature.