The Alexandrian texts were incorporated into the body of classical Greek literature that was preserved, catalogued and studied by the scholars of the Hellenistic period. From then until the fourth centuryAD, copies of Demosthenes' orations multiplied and they were in a relatively good position to survive the tense period from the sixth until the ninth century AD. In the end, sixty-one orations attributed to Demosthenes survived till the present day (some however are pseudonymous). Friedrich Blass, a German classical scholar, believes that nine more speeches were recorded by the orator, but they are not extant. Modern editions of these speeches are based on four manuscripts of the tenth and eleventh centuries AD.