In De Trinitate 10, Augustine offers an argument that seemingly proceeds from certain premises about self-knowledge to the conclusion that the mind is incorporeal. Although the argument has sometimes been compared to later Cartesian arguments, it has received relatively little philosophical attention. In this paper, I offer a detailed analysis and original interpretation of Augustine's argument and argue that it is not vulnerable to some of the main objections which have been raised against it. I go on to argue that (...) while an important part of Augustine's argument does face several hitherto neglected objections, Augustine's ultimate case for the incorporeality of the mind is somewhat different and more successful than one might initially think. (shrink)