The need of a reliable manual of Patrology in English has been so long felt by teachers of that science that little excuse is needed for the present attempt to place one within reach of all concerned. During the nineteenth century much patristic material, both new and important, has been discovered, East and West. In the same period there has come about a notable perfection of the methods and instruments of scholarly research, while literary criticism has scored some of its remarkable triumphs in the province of early ecclesiastical literature. Above all, the intense and crucial conflict concerning the genuine nature and actual History of the primitive Christian teaching has perforce attracted the combatants to one great armory of weapons: the writings of the Christian Fathers. Excavation and research among the ancient monuments of Roman imperial times have naturally quickened interest in all contemporary literary material. An intelligent study of the early middle ages has made clear the incalculable influence exercised upon the barbarian world by the Christianized civilization of the fourth and fifth centuries; the manners, politics, and tongues of the ancestors of the modern Western world can no longer be studied scientifically apart from a sound knowledge of what our earliest Christian masters were. At this distance, such knowledge must, of course, be gathered, to a great extent, from their literature, or rather from the remnants of it that survive. When such competent judges as the modem Bollandists agree that the «Patrologie» of Dr. Bardenhewer has no superior, for abundance of information, exactness of reference, and conciseness of statement, we may take it for granted that the work is well fitted to introduce all studious Christian youth into the broad and pleasant sanctuary of patristic science. The experience of ecclesiastical teachers confirms this judgment; for the work has already been translated, into both French and Italian.