This article analyzes the definition of res in two places of Augustine's works, namely, De dialectica, ch. 5, and De doctrina christiana, I, ii, 2. In these places, the concept of res is treated in relation to the concept of sign (signum). In the first text, Augustine suggests that with our words we mean things by expressing ideas of those things. According to the second text, something is a thing only insofar as it is not being used currently as a (...) sign, given that anything can be used as a sign. (shrink)