  The core set of ideas and doctrines from which medieval philosophers developed their semiotic theories was provided to them mainly by two late ancient authors. Besides Boethius (480–528), who transmitted Aristotelian semantics to the Latin Middle Ages, Augustine's (354–430) doctrine of sign is the most important junction of ancient and medieval theories of sign and signification. Augustine's doctrine also has to be seen as a decisive turning point in the history of semiotics.