Obviously the great work on the Faith, De Fide, must be included, and this implied the addition of that on the Holy Spirit. Then the treatise on the Duties of the Clergy, as throwing much light on the ideas of the Fourth Century as to what was expected of ecclesiastics, seemed to claim a place. And after these the difficulty becomes very great. It is unfortunate that the limitations of space do not admit of the inclusion of all the dogmatic and ascetic treatises. Similarly, one would have been glad to insert the addresses on the deaths of the two Emperors Valentinian and Theodosius. More, also, of his letters might well have been added, though, as they have appeared in full in the Oxford “Library of the Fathers,” this is a matter for less regret.