Phallus

The triangle takes form in the parental use, and reproduces itself in the conjugal use. We do not yet know what forces bring about this triangulation that interferes with the recording of desire in order to transform all its productive connections. But we are able at least to follow, abstractly, the manner in which these forces proceed. We are told that partial objects are caught up in an intuition of precocious totality, just as the ego is caught up in an intuition of unity that precedes its fulfillment. (Even in Melanie Klein, the schizoid partial object is related to a whole that prepares for the advent of the complete object in the depressive phase.) It is clear that such a totality-unity is posited only in terms of a certain mode of absence, as that which partial objects and subjects of desire "lack.". Consequently, everything is played out from the start: everywhere we encounter the analytic process that consists in extrapolating a transcendent and common something, but that is a common-universal for the sole purpose of introducing lack into desire, in situating and specifying persons and an ego under one aspect or another of its absence, and imposing an exclusive direction on the disjunction of the sexes.

AO72:2

Such is the case in Freud: for Oedipus, for castration, for the second phase of the fantasy "A Child Is Being Beaten," or again for the famous latency period where the analytical mystification culminates. This common, transcendent, absent something will be called Phallus or Law, in order to designate "the" signifier that distributes the effects of meaning throughout the chain and introduces exclusions there (whence the oedipalizing interpretations of Lacanism). This signifier acts as the formal cause of the triangulation - that is to say, makes possible both the form of the triangle and its reproduction: Oedipus has as its formula 3+1, the One of the transcendent phallus without which the terms considered would not take up the form of a triangle
AO72:3