This paper discusses the content and philosophical background of the extensive passages in thefirst book of Diodorus Siculus that are in general (though not without some recent scepticism,which, however, seems excessive) considered to be derived from the Aegyptiaca of the early Hellenisticwriter Hecataeus of Abdera. Apparently, Hecataeus borrowed (but also tried to improveon) some ideas he found in Plato’s Republic to present Egypt as a kind of ideal constitutionalmonarchy; a recent attempt to unmask this picture as a dystopia seems misguided.