Even if Plato never claimed to be a ‘historian of philosophy’, there are in his dialogues many references to previous philosophers. Apart from his works on the Sophists, which do not claim to faithfully expose the ‘philosophy’ of their authors, we find in Plato’s dialogues comments and sometimes quotations from the Presocratics, from Thales to Philolaos. In some cases, Plato adds the name of the quoted philosopher, but sometimes he leaves to the reader the task of finding out who the commented or quoted author is. This is the case with Melissos in a passage of the Sophist (244b), where his name is not quoted, but an anonymous monistic philosopher expounds a literal quotation of the philosopher: ἓν μόνον ἔστιν (fr. B 8.1 DK).