The various gradations of the hierarchy were preserved as before the Arab occupation. The archbishops had the usual number of suffragans subject to their jurisdiction; the lower orders of the clergy, their clerks, choristers, readers, and other subordinates. To exercise the office of priest it was necessary for both parents to be of the Christian faith; if the father were a Moslem, the law of the conqueror interposed its claim upon the candidate, who, regarded as a Mussulman by birth, was liable to condemnation for apostasy. Unlike the canonical practice of other Catholic countries, an ecclesiastic was eligible to offices of the most distinguished rank, even to the primacy itself, without being compelled to pass through the intermediate grades of the priesthood. There was no diminution of pomp or solemnity in the celebration of the rites of Christian worship. Councils for the regulation of church government and discipline were even more frequent than under the Visigoths; during the ninth century, three were held at Cordova alone in less than thirty-five years. In many of the monasteries, schools were established for the communication of instruction, on both sacred and profane subjects, to those whose religious scruples prevented them from profiting by the splendid opportunities afforded by the great Arab institutions of learning. In some of these religious houses were extensive libraries, composed for the most part, however, of treatises of patristic science, polemics, and hagiology. To St. Eulogius, alarmed by the increasing influence of the Mussulman academies, which offered irresistible attractions to the Christian youth, is due the credit of having introduced to the notice of his countrymen the works of Horace, Virgil, Juvenal, and others of the Latin classics, copies of which he obtained during a visit to Navarre.