though he reigned a hundred and fifty years later, represents rather the patriarchal idea than the papal. Leo was at the same time the fij-st important theo- logian in the chair of Rome, surpassing in acnteness and depth of thought all his pcedecessors, and all his successors down to Gregory I, Benedict XIV. placed him (a. d. 1714) in the small class of doctores ecclesicB, or authoritative teachers of the catholic faith. He battled with the Manichtean, the Priscilli- ' Ep. ad Cone. Carthag. and Ep. ad Concil. Milev., both in 416. In reference to this decision, which went against Pelagius, Augustine uttered the word so often quoted by Roman divines: '■'■ Causa finita est; utinam aliquando finiatur error." But when Zosimus, the successor of Innocent, took the part of Pelagius, Augustine and the African churcl^ boldly opposed him, and made use of the Cyprianic right of protest. " Circumstances alter cases." 316 THIRD PEEIOD. A.D, 311-590. anist, the Pelagian, and other heresies, and won an immortai name as the finisher of the orthodox doctrine of the person of Christ. The time and place of the birth and earlier life of Leo are unknown. His letters, which are the chief source of informa- tion, commence not before the year 442. Probably a Roman ' — if not one by birth, he was certainly a Eoman in the proud dignity of his spirit and bearing, the high order of his legisla- tive and administrative talent, and the strength and energy of his will — he distinguished himself first under Coelestine (423- 432) and Sixtus III. (432-440) as archdeacon and legate of the Roman church. After the death of the latter, and while himself absent in Gaul, he was elected pope by the united voice of clergy, senate, and people, and continued in that office one-and-twenty years (440-461). His feelings at the assumption of this high office, he himself thus describes in one of his sermons : " Lord, I have heard your voice calling me, and I was afraid : I considered the wort which was enjoined on me, and I trembled. For what proportion is there between the burden assigned to me and my weakness, this elevation and my nothingness ? What is more to be feared than exalta- tion without merit, the exercise of the most holy functions being intrusted to one who is buried in sin ? Oh, you have laid upon me this heavy burden, bear it with me, I beseech you ; be you my guide and my support." During the time of his pontificate he was almost the only great man in the Roman empire, developed extraordinary activity, and took a leading part in all the affairs of the church. His private life is entirely unknown, and we have no reason to question the purity of his motives or of his morals. His official zeal, and all his time and strength, were devoted ^ As Quesnel and most of his successors infer from Prosper's Chronicle,