It was Isidore who fostered in Spain the growth of Christian culture amidst the barbarism of Europe which had resulted from the conquests of the Visigoths. He presided at the fourth Council of Toledo in 633, the most celebrated in Spain, where he succeeded in enacting a decree that a cathedral school should be established in every diocese, to teach every known branch of knowledge ; that is, the liberal arts with law and medicine, as well as Greek and Hebrew. In these Spanish schools Aristotle was studied long before the Arabs had brought him to the attention of the rest of Europe. Isidore himself wrote many useful books, full of learning ; such as a dictionary of synonyms, a treatise on physical geography and astronomy, a history of the world, a biography of great men, extensive biblical and ecclesiastical studies, and a history of the Goths, Vandals, and Suevi. He also compiled an encyclopaedia of universal knowledge, in twenty volumes, which for centuries was everywhere used as a textbook ; for which reason he was known as the Schoolmaster of the Middle Ages. To his is also ascribed the completion of the Missal and Breviary of the Mozarabic Rite for the use of the Goths, which Leander had begun to arrange from the earlier Spanish liturgy. And he greatly assisted the monastic Orders by the regulations which he gave them.
He finished the work of converting the Visigoths from Arianism, and in 619, at the second Council of Seville, stamped out the strange heresy of the Acephali which was just then arising. He was a great example in the episcopate of all good works, and zealously laboured for the restoration of ecclesiastical discipline. To this end, he continued to organize the Spanish Church along the lines Leander had begun, into a system of representative government through synods, which was the precursor of the parliamentary secular governments of a later day. After governing his See for about forty years, he passed to heaven at Seville, in the year 636, and was buried in his cathedral church, between Saints Leander and Florentina. Many years later, when the Moors had overrun that region, his relicks were ransomed at a great price, and enshrined at Leon, where they are still venerated.
Collect:O God, by whose providence blessed Isidore was sent to guide thy people in the way of everlasting salvation : grant we beseech thee that as we have learned of him the doctrine of life on earth, so we may be found worthy to have him for our advocate in heaven. Through Jesus Christ thy Son our Lord, who livest and reignest with thee, in the unity of the Holy Ghost, ever one God, world without end. Amen.