The great Ambrose had been called from the magistrate's chair to be bishop of this important city; and his character and ability made a great impression on Augustine. But Augustine was kept from acknowledging and submitting to the truth, not by the intellectual difficulties which he propounded as an excuse, but by his unwillingness to submit to the moral demands which Christianity made upon him. At last there came one great struggle, described in a passage from the 'Confessions' which is given below; and Monica's hopes and prayers were answered in the conversion of her son to the faith and obedience of Jesus Christ. On Easter Day, 387, in the thirty-third year of his life, he was baptized, an unsubstantiated tradition assigning to this occasion the composition and first use of the _Te Deum_. His mother died at Ostia as they were setting out for Africa; and he returned to his native land, with the hope that he might there live a life of retirement and of simple Christian obedience. But this might not be: on the occasion of Augustine's visit to Hippo in 391, the bishop of that city persuaded him to receive ordination to the priesthood and to remain with him as an adviser; and four years later he was consecrated as colleague or coadjutor in the episcopate. Thus he entered on a busy public life of thirty-five years, which called for the exercise of all his powers as a Christian, a metaphysician, a man of letters, a theologian, an ecclesiastic, and an administrator. Into the details of that life it is impossible to enter here; it must suffice to indicate some of the ways in which as a writer he gained and still holds a high place in Western Christendom, having had an influence which can be paralleled, from among uninspired men, only by that of Aristotle. He maintained the unity of the Church, and its true breadth, against the Donatists; he argued, as he so well could argue, against the irreligion of the Manichaeans; when the great Pelagian heresy arose, he defended the truth of the doctrine of divine grace as no one could have done who had not learned by experience its power in the regeneration and conversion of his own soul; he brought out from the treasures of Holy Scripture ample lessons of truth and duty, in simple exposition and exhortation; and in full treatises he stated and enforced the great doctrines of Christianity.