The progress of modern studies toward an exact edition of St. Athanasius, De incarnatione, is notably advanced in this double volume, by Professor Ryan of the College of William and Mary, and by Professor Casey of Brown University. We shall turn to their work with readier appreciation if we first recall several previous contributions. One of these was the edition by Archibald Robertson, published more than fifty years ago (London, 1893), based on the Codex Seguerianus (S), a twelfth century parchment in the Bibliothèque Nationale, first collated for the Benedictine edition of Athanasius in 1698. Casey and Ryan were well advised in adopting Robertson's text as the constant norm of their collations. A great boon is conferred on their readers by Casey's reprint of Robertson, page by page and line by line, as an appendix of Part II.