  One conspicuous feature of Byzantine literary culture in general, and the study of philosophy in particular, is its relative continuity with ancient Greek literary culture. In Byzantium, the treasures of this culture never had to be discovered, as they were in the 9th-century Arab East, or even rediscovered, as in the 12th-century Latin West. At all times, Homer’s Iliad remained the most important textbook for secondary education. Still, this continuity is not absolute: considerable parts of the literary heritage were pushed into oblivion in periods of cultural decline, some of which were eventually lost, whereas others survived to attract new attention during the subsequent periods of intensified activity. The most important periods of intensified activity, so far as the history of philosophy is concerned, are: (1) the late Phrygian to early Macedonian (842–959), when ancient philosophical texts were saved for posterity by the production of new copies in minuscule script; (2) the late Macedonian to early Komnenan (1042–1143); and (3) the early Palaiologan (1259–1341). Each of these periods was ushered in by the establishment of an Imperial School of Philosophy in Constantinople. Apart from the Imperial Schools, private tutorial played an important part in higher education, some teachers attaining considerable fame, for example Nikephoros Blemmydes (1197–c. 1269), Gregory of Cyprus (1241–1290), Nikephoros Gregoras (1293/94–1360/61) and George Gemistos Plethon (c. 1360–1452). In the Komnenan (1182–1204) and Palaiologan (1259–1453) periods, the Patriarchal School loomed large, at times existing side by side with the Imperial School, but apparently specially designated for the education of the clergy.