  Greek philosophical texts are usually known to us through the medieval manuscript tradition, transmitted, in the best cases, by manuscripts of the ninth or tenth centuries CE that were already, by that date, the products of many generations of copies, and perhaps too of a couple of scholarly editions. Fragments of ancient papyrus manuscripts give punctual insights into the state of some of these texts in earlier periods, from the late third century BCE to the sixth century CE, and can thus be used to help gauge the accuracy of the later manuscript tradition.