In addition to the critiques of the subject offered by Nietzsche and Heidegger, many postmodernists also borrow heavily from the psycho-analytic theories of Jacques Lacan.  Lacan's distinctive gesture is his insistence that the Freudian unconscious is a function, or set of functions, belonging to language and particularly to the verbal exchanges between the analyst and analysand during the analytic session (see Lacan 1953–55).  For Lacan, the subject is always the subject of speech, and that means speech directed toward an other in relation to whom the subject differentiates and identifies itself.  On this view, language is a feature of the “symbolic order” of society, which is constituted as an economy of signifiers, through which animal need becomes human desire, whose first object is to be recognized by the other.  However, desire ultimately aims for something impossible: to possess, to “be,” or to occupy the place of the signifier of signifiers, i.e. the phallus.  Insofar as the phallus is nothing but the signifying function as such, it does not exist.  It is not an object to be possessed, but is that through which the subject and the other are brought into relation to begin with, and it thus imposes itself upon the subject as a fundamental absence or lack that is at once necessary and irremediable (Lacan 1977, 289).  Hence the subject is forever divided from itself and unable to achieve final unity or identity.  As the subject of desire, it remains perpetually incomplete, just as Dasein in Heidegger exists “beyond itself” in temporal ecstasis.