This book presents the first refined stemma of the transmission of the Greek text with a resultant revision of it, together with a detailed commentary section. Newly deciphered passages of text from the Greek Palimpsest M (11th cent.), one of the oldest extant Greek manuscripts, are edited and incorporated in the revision. A comprehensive chapter is devoted to demonstrating the secondarity of the "short text" edited by Philonenko, which turns out to be the product of medieval copyists. The second part of the book undertakes an edition of an important document from the Middle Ages, the second Latin translation, and examines it from the perspectives of palaeography, philology and Church history.