This thesis explores the philosophical dimension of the autobiographical discourse presented by Plato in the text known, since the compilation made by Trasimacus, as the Seventh Letter. The tradition of commentary and interpretation has established the use of reading the letter as a document of great historigraphical importance, as a source of information about the political affairs in Siracuse during the IV century b. C., and about Plato himself – but not as a work of philosophical nature (except for the digression in 341a-345c). The present research proposes a different idea: a piece of writing in which Plato presentes, examins and justifies his own biographical trajectory has in itself a philosophical nature, insofar as it fulfills the socratic-platonic appropriation of the Delfic precept “Know thyself”. To defend the hypothesis, the research analyses the history of the Delfic principle in Ancient Greece, and the deep meaning of the mentioned appropriation in the wider context of Plato’s works. Besides, the present thesis also delas with the controvert subjetc of the letter’s authenticity, challenged by some scholars. In dealing with this matter, the research will present a critic inventory that sorts in kinds all the arguments, both contrary and favorable to the authenticity – the ones based on style, stylometry, History and philosophy – and, at last, it takes a stand on that issue.