The most important philologist of this period was the Patriarch of Constantinople, Photios. A highly educated man with extensive knowledge of the Greek classics and Byzantine literature and theology, Photios has left us with several invaluable works: a dictionary of ancient Greek, the Lexeon synagoge kata stoicheion, 18 homilies, 193 epistles and, most important, the Bibliotheke (Bibliotheca). This (also known as the Myriobiblon) is a great collection of ancient and Byzantine literature, although the title of the manuscripts is Apographe kai synarithmesis tov anegnosmenon hemin biblion (List and Description of Books We Have Read). This collection contains 279 chapters, often with a lengthy summary of each work, comments and/or an evaluation. Almost 60 of the 90 classical and Byzantine secular works Photios included in his collection, and about 100 of the Christian texts would be either completely unknown or only partially known to us if it had not been for the work of this remarkable scholar. Apart from Photios, the most eminent student of classical letters was Arethas, Archbishop of Caesarea in Cappadocia (circa 902-944). Among his achievements was to re-issue Plato's and Aristotle's classical philosophical works and to copy, from brittle papyrus to more durable parchment, many other important ancient writers. A 10th century work that matches the best of Constantine VII Porphyrogennetos's age is the Lexikon tes Soudas (Soudas΄ Dictionary), the most comprehensive of Byzantine dictionaries. Its virtue lies in the fact that it attempted to combine the usual etymological and lexicographical information with entries on literature, history, philosophy and other sciences. This, combined with its invaluable information on ancient and Byzantine litterature, makes the Souda a must for all students of Greek and Byzantine literature.