Freud first theorizes the drive through Wilhelm Fliess’s theory of bisexuality, which proposes that human life is structured by the periodic expression of a masculine and a feminine substance. Long after his break with Fliess, Freud maintains elements of Fliess’s theory, arguing that the feminine eroticizes the body and orients the drive toward its impossible object and that analysis is interminable because in both men and women the feminine is rejected by the ego. Lacan largely passes over Freud’s bisexual thesis. Through his reading of Wittgenstein, whose Tractatus takes up Fliess’s theory of bisexuality through the intermediary of Otto Weininger, however, Lacan formalizes the impasse between the feminine as what mobilizes the drive and the ego as it is constructed in language. Lacan’s reading of logical form in Wittgenstein opens to a writing of the drive in its relationship to a logical object that is itself missing from reality.