With the labors of St. Gregory the influence of the Church upon the course of musical development by no means ceased. At various epochs in its history synods, councils and popes have effected various reforms, every reform consisting in barring out a certain amount of novelty which had crept in, and in a supposed "restoration" of the service to its pristine purity. The restoration, however, has never been complete. Church music, like every other department of the art, has gone on in increasing complexity from the beginning until now. The main difference between the Church and the world in any century consists in drawing the line of the permissible at a different point. One of the latest reforms was that begun by Pope Marcellus and the Council of Trent, which ordered from Palestrina an example of church music as it should be. Incidentally, in another direction, the Church has been of very great influence upon the course of musical development. The great cathedrals of the commercial centers of the world, in the effort to render their service worthy of the congregation, have afforded support to talented composers in all ages, and some of the most important movements in music have been made by ecclesiastics or officials deriving support from these sources. More extended particulars of this part of her influence will be given later. It may suffice to mention the cathedrals of Westminster and St. Paul in England, of Notre Dame in Paris, to which we owe the old French school and the beginning of polyphony; the cathedral at Strassburg, which supported important musicians; Cologne, where the celebrated Franco lived; St. Mark's, at Venice, where, from about 1350 to the end of the last century, an extremely brilliant succession of musical directors found a field for their activity. CHAPTER XI. THE DIDACTIC OF MUSIC FROM THE FIFTH CENTURY TO THE FOURTEENTH. I.