Abstract Augustine’s understanding of language is derived from his understanding of signs, signa, itself based on his distinction between res and signum, ‘thing’ and sign, developed especially in De Doctrina Christiana, I. The way signs refer to things is mostly a matter of convention—wholly so in the case of words (which is what his understanding of language largely amounts to). Language communicates by using words for concepts, and the Platonist in Augustine is inclined to mistrust it, for communication by language seeks to convey the intelligible, perceived internally, across the external by the sensible, and so doubly prone to misunderstanding. The Platonist in Augustine is, however, caught out by the Christian in Augustine, for whom the pre-eminent means of communication in God’s by means of the Incarnate Word. As Augustine contemplates this, he discerns a means of communication by means of a communion in love, which frustrates his Platonic scepticism.