In 2005, an Egyptian dialogue’s editio princeps was published, named by its editors the ‘Book of Thoth’. While prior research on the relation between this dialogue and the Corpus Hermeticum could not identify far reaching parallels, another relation has not been taken into account yet: the relation to Plato’s critique of writing in the Phaedrus. The present article argues that very likely the Book of Thoth forms a source of the Platonic text, to which Plato responds with a diametrically opposed (...) criticism. To underline the argument, literal and thematic parallels are pointed out in a first step. Then, secondly, the focus is put on the order of the two texts. Finally, a systematic comparison between the Platonic and the Egyptian understanding of scripture underscores the argument. Thematic parallels and literal correspondences are numerous and therefore suggest excluding a similarity by accident: In the Book of Thoth we grasp a concrete Egyptian source of Plato for the first time. (shrink)