Any didactic review of Lacan's Seminars is, perhaps, deeply ironic. The seminars themselves were oral performances, and this volume, like all the other Seminars, consists of notes of Lacan's lectures, edited in French by his son-in-law, Jacques-Alain Miller. Lacan's pedagogical technique relied on the ambiguities of meaning in language, particularly spoken language, to evoke a quasi-poetic or religious sense that transcends words, while simultaneously he elaborated a structured psychoanalytic theory, which he insisted was merely an exegesis of what was implicit in Freud's work.
With that said, this volume, the second of his Seminars presented in the 1954 - 1955 academic year, is as good a place as any to plunge into his work. These lectures focus on Lacan's concept of the "symbolic order," and the radical alienation of the human subject from that order, while, simultaneously, the same order is constitutive of the subject, telling the subject who s/he "is" (to the extent s/he "is" anything!). In this and later Seminars, Lacan will develop these ideas into his notion of the subject's relation the Other (with a capital "O"), and the idea of the split subject, who is caught between his or her unconscious and the symbolic order, structurally separated from both, and who only appears momentarily when he or she speaks "I."
The reputation of Lacan's work for being extraordinarily obscure and difficult is well deserved. All I can say is that I have found it worth the effort to attempt to grasp his thinking. Some knowledge of Freudian theory is a prerequisite to make any sense of what Lacan is talking about, and a familiarity with continental philosophy, particularly Hegelian philosophy, is very helpful. I've also found Lacan For Beginners (For Beginners (Steerforth Press) and Introducing Lacan, 3rd Edition to be extremely helpful starting points to make sense of Lacan's difficult material.