some out-of-the-way places", claimed, on the model of the Old Testament priesthood, the right to father children, he recalled that in Old Testament times even lay people were obliged to observe continence on the days leading to a sacrifice, and commented: "If such regard was paid in what was only the figure, how much ought it to be shown in the reality!" Yet more sternly he wrote: "(Saint Paul) spoke of one who has children, not of one who begets children." Medieval Christendom Beyond the fact that clerical celibacy functioned as a spiritual discipline, it also was guarantor of the independence of the Church and of its essential dimension as a spiritual institution ordered toward ends beyond the competence and authority of temporal rulers. During the decline of the Roman Empire, Roman authority in western Europe completely collapsed. However, the city of Rome, under the guidance of the Catholic Church, still remained a centre of learning and did much to preserve classical Roman culture in Western Europe. The classical heritage flourished throughout the Middle Ages in both the Byzantine Greek East and the Latin West. Philosopher Will Durant argues that certain prominent features of Plato's ideal community were discernible in the organization, dogma and effectiveness of the medieval Church in Europe: In his book The Ruling Class, Gaetano Mosca wrote of the medieval Church and its structure: It is sometimes claimed that celibacy became mandatory for Latin Church priests only in the eleventh century; but others say, for instance: "(I)t may fairly be said that by the time of St. Leo the Great (440–61) the law of celibacy was generally recognized in the West," and that the eleventh-century regulations on this matter, as on simony, should obviously not be interpreted as meaning that either non-celibacy or simony were previously permitted. However there is abundant documentation that up to 12th century many priests in Europe were married and that their sons would often follow their path which made the reforms difficult to implement. Reformation period Celibacy as a requirement for ordination to the priesthood (in the Western Church) and to the episcopate (in East as well as in West) and declaring marriages of priests invalid (in both East and West) were important points of disagreement during the Protestant Reformation, with the Reformers arguing that these requirements were contrary to Biblical teaching in , , and , and implied a degradation of