§5. History of Doctrine . For ancient sources see articles Heresiology and Person of Christ in D.C.B., vols. iii., iv. The modern classics are the works of Petavius , de Trinitate (in vols. ii. and iii. of his De dogmat. Theol .) of Thomassinus , Dogmata Theologica , and of Bull , Defensio fidei Nicænæ (maintaining against Petav. the fixity of pre-Nicene doctrine). Under this head we include Newman’s Arians of the Fourth Century , an English classic, unrivalled as a dogmatic and religious study of Arianism, although unsatisfactory on its purely historical side. (Obsolete chronology retained in all editions.) The general histories of Doctrine are of course full on the subject of Arianism; for an enumeration of them, see Harnack, §2 of his Prolegomena. In English we have Shedd (N.Y., 1863, Edinb., 1884), Hagenbach (Clark’s Foreign Theol. Lib .), and the great work of Dorner (id.). The most important recent works are those of Harnack , Dogmengeschichte (1886, third vol., 1890), a most able work and (allowing for the prepossessions of the Ritschl school) impartial and philosophical; and Loofs , Leitfaden zur Dogmengeschichte (2 ed., 1890), on similar lines, but studiously temperate and fair. Both works are much used in this volume (quoted commonly as ‘Harnack,’ ‘Loofs,’ simply. Harnack, vol. i., is quoted from the first edition, but the later editions give comparative tables of the pages). For Councils and Creeds , in addition to the works of Hefele and Bright mentioned §4 c., see Heurtley Harmonia Symbolica ; Hahn , Bibliothek der Symbole ; Hort , Two Dissertations (1876), indispensable for history of the Nicene Creed; Swainson , Nicene and Apostles’ Creed , 1875; Caspari , Ungedruckte u.s.w. Quellen zum Taufsymbol u.s.w . (3 vols. in 2, Christiania, 1866–1875), and Alte und Neue Quellen , ib. 1879; one of the most important of modern patristic works.