The pope, who had great diplomatic gifts, endeavoured to es tablish good relations with all countries. He obtained the insti tution of a Russian embassy to the Vatican, and even estab lished diplomatic relations with Japan. A council of bishops of all the South American States was held in Rome in 1899. The Catholic hierarchy, which now extended over all parts of the world, was increased by nearly 30o dioceses and vicariates. Leo XIII. was a born ruler, and was inspired as a teacher by abun dant knowledge of the world and of life.
The Vatican library and archives were developed on the lines adopted by Leo XIII., and the new picture gallery was created. The Italian bishops were given instructions for the care of ecclesiastical archives and the preservation of monuments. Pius also undertook the reform of Church music, and encouraged the use of the old Gregorian chants.
The pope, as bishop of Rome, frequently preached sermons; he recommended frequent communion as a means of develop ing spiritual life, and suggested that children should be admitted to communion as early as possible. He carried out a number of liturgical reforms, and laid down rules for the secular and regu lar clergy, who were instructed to interest themselves in social questions. Pius did important work in connection with the codifi cation of ecclesiastical law. Under his instructions, the rules which remained valid for the present day were extracted in a clear and definite form from the chaotic mass of laws which had accumulated in the course of centuries, some of which no longer corresponded to modern requirements. He did not live to see the completion of this work, the new Codex iuris ecclesiastici, but certain of its provisions, including those relating to marriage, were put into force during his life-time.
A great stir was created by the pope's manifesto against mod ernism (1907). In this he condemned all tendencies, whether in Catholic theology or elsewhere, which aimed at the reform of dogma. He demanded that the clergy and teachers of theology should take a special oath disavowing modernism, a movement which had its headquarters in France and Italy and threatened to cause a weakening of the faith in those countries. Pius was not opposed to the modern historical outlook, and recognized the justification of a development of Church doctrine on the basis of incontrovertible researches; but as the guardian of Cath olic dogma he could not allow that the supernatural sources of revealed religion should be deprived of their specifically ecclesiasti cal character by false evolutionism, and that faith and knowledge should be completely separated from one another.