Fortunately these strict principles were not generally followed in practice. Most of the Greek and Latin Fathers not only studied the classics, but availed themselves of the lectures of the most celebrated professors of their own time, whether Christian or pagan; and so they were enabled to meet their opponents on equal terms--to refute the philosophers by philosophy, and the rhetoricians by rhetoric, to point out the turpitude of the gods of Greece and Rome, and to contrast in glowing language of the most fervid and lofty eloquence, the nobility of Christian doctrine, and the purity of Christian morals with the false ethics and unclean practices of the pagan religion. In the fifth century, however, of the Christian era a change gradually took place. With the decline of paganism the great schools in the various cities of the empire began to decay, and were finally closed during the reign of Justinian. Meanwhile episcopal schools for the education of the clergy were further developed and enlarged. St. Augustine at Hippo, St. Ambrose at Milan, St. Eusebius at Arles, had founded establishments of this kind, and the fame of those great and learned prelates soon attracted large numbers of pupils to their episcopal seminaries. The Churches of Africa eagerly sought for pupils of St. Augustine's school to fill the vacancies occurring in their sees, and many other pupils from the more celebrated of these seminaries were raised to the highest dignities in the Church. But with the spread of monasteries in the West during the fourth and fifth centuries a new and vigorous impulse was given not only to all branches of sacred learning, but indirectly to profane literature also. Sacred reading and sacred study was deemed an essential portion of monastic work. Legere, orare, laborare--study, prayer, and labour--was the daily work of the monk; and if it was not always the task of the individual it certainly was of the community. Of course the sacred volume was the primary object of their study; but almost all branches of human learning are aids to the study and right understanding of Scripture, and were cultivated for that purpose. Then again, monasticism was, as we have seen, intended to be self-sufficing. It was a world of its own, a city of God, producing for itself all that is needed in the physical and moral order. So the monks found it necessary to cultivate the ornamental as well as the useful arts of life. They delved and sowed and reaped; but they also built their churches, and decorated their altars, and wrote their books, and sang in choir, and computed their festivals, and healed the sick. There must be amongst them physicians, astronomers, geometers, and musicians, as well as moralists, preachers, scribes, and illuminators. Every branch of human knowledge was useful, if not necessary, for a great monastery, and they all came to be cultivated in the great monastic schools.