Testimonia platonica

A modern scholar who recognized the importance of the unwritten doctrine of Plato was Heinrich Gomperz who described it in his speech during the 7th International Congress of Philosophy in 1930. All the sources related to the unwritten doctrine (ἄγραφα δόγματα) have been collected by Konrad Gaiser and published as Testimonia Platonica. These sources have subsequently been interpreted by scholars from the German Tübingen School such as Hans Joachim Krämer or Thomas A. Szlezák.