A while back I argued that Anselm’s doctrine of the divine locutio (“utterance,” “expression”) helped resolve an ambiguity at the heart of Augustine’s doctrine of the divine Verbum, namely his ambivalence between a more verbal or linguistic model for understanding the second person of the Trinity on the one hand and a more visual and hence intellectual model on the other. Related to this is another ambiguity in Augustine’s thought, this time within his philosophy of language itself. To develop, for the time being, just one side of that tension, John Milbank has argued that there are significant elements in Augustine’s theology of language which push against the kind of “linguistic rationalism” that dominated much ancient, patristic, and medieval reflection on the subject. Milbank draws particular attention to the Aristotelian and Stoic “semantic triangle” of word-idea-referent, which he criticizes as implying an “instrumentalist view of the relation of language to thought, a strict distinction between ‘sign’ and ‘thing’, and a general denial of any sort of ‘essential’ relation between sign and thing signified.” Yet it was also the Stoics who first “decisively modified” the semantic triangle “by interpreting the meaning-content (semainomenon) [of words] not as eternal “Idea,” nor as psychological “thought,” but rather as a lekton, a position within a system of signification.” One of virtues of this revised understanding of the relationship between words and their meaning, on Milbank’s view, was its insight into the irreducibly linguistic character of the act of signification, such that “the lekton, as an ‘incorporeal’ sign of something else, always connotes other elements in a moving continuum, rather than denotes extra-linguistic onta… The ‘incorporeal’ character of these lekta does not indicate any Platonic, eternal status, but rather a ‘temporally indefinite’ character.” Put in modal terms, in the place of Aristotle and Plato’s “semantic possibilism” (as we might deem it), according to which it is a prior realm of fixed, abstract thought and eternal ideas that provides the possibility of the meaningfulness of words and things, the Stoic doctrine of lekta substituted a “semantic actualism” according to which the meaning of a word depends on all the other words there are and hence may be connoted within the dynamic “continuum” of a given “system of signification.” They are traces of this Stoic modification of the semantic triangle, finally, that Milbank finds evidence of in Augustine when, for example, and following the Stoics, he “speaks of a verbum cordis or verbum mentis, rather than just ‘a thought’,” or when “Augustine is so aware of the sign-character of words, and the indispensability of the artificial system of language for thought, that in De Magistro he declares that one can give the meaning of a word only by another word, or else by a gesture which is still a sort of sign.” Elaborating on Augustine’s doctrine of the “inner word” in particular, Milbank finds here that Augustine “construes thought as ‘intentional’, or as having a sign-character (the Stoic lekton) which, especially in the De Trinitate, promotes a non-substantive, relational ontology…” (This move is paralleled, as we shall see later, in his commentary on Genesis, where he likewise shifts the source of creaturely possibility from the Platonic divine ideas to the less substantive, more relational and immanent ontology of the Stoic rationes seminales or “rational seeds.”) Indeed, Milbank suggests that
Augustine actually goes further than the Stoics in one respect, by becoming the first person in history unequivocally to place the linguistic word itself in the category of sign: verbum est uniuscuiusque rei signum. For the Stoics the word itself still stood in a relationship of definitional equivalence to the lekta, if not to referential res (as for Aristotle). As Umberto Eco has pointed out, Augustine’s conflation was a potentially momentous innovation, because by bringing words under a category traditionally to do with ‘natural’ relationships of typical implication (as the sequence fire/smoke, considered generically) Augustine opened the way to seeing that word and ‘dictionary definition’ are never fully reciprocal. Quite to the contrary, words can only be explicated ‘intensionally’, through a process of semiotic inference which relates no longer (as for the Stoics) more or less readily to nature, but only to a particular cultural-linguistic ‘segmentation’ of reality.
In each of these ways, in sum, Augustine dimly foreshadows the later Renaissance humanist view of thought as sign—a “Trinitarian redefinition of the ideas as ‘word’ or ‘art’”—and beyond that, the eighteenth-century insight of such Christian philosophers as Berkeley, Hamann, Herder, and Vico into the “indispensability of language for thought,” the ultimate “impossibility of distinguishing ‘sign’ from ‘thing’,” and the recognition of “reality as constituted by signs and their endless ramifications” that anticipate and hence which allow for a more “positive assessment of language.”
 Milbank, The Word Made Strange, 84.