=Paris the Centre of Europe=.—It was natural that these two great changes should take place in Paris, at that time the centre of wealth and learning for all Europe. Paris, in addition to its many other advantages, had long possessed a great university which had produced many scholars and theologians. The influence of the Church in all art was then paramount, for all art was employed in the service of the Church; Architecture gave to the Church its Gothic cathedrals; Painting and Frescoing its marvelous interior decorations; while Music made possible the richer forms of the service or liturgy. In that sense the Church, in its centre of theological study, would undoubtedly react on the practice of music and produce more beautiful forms for the service. In this period it is worthy of note that all the _famous musicians_, as before, were _monks_, or men employed in the Church, and the reason for this condition is plain: there was no art of music outside of the Church. =Measured Music=.—Just as the use of many voices produced singing in parts, so did it produce Measured Music. To make it possible to use more than two parts at the same time it was necessary to have some definite agreement as to the value of the notes, in order to have certain uniform times for beginning, ending and performing the different portions of a composition agreeably; and so Measured Music was born. It may be said here that the different metrical divisions were not shown by means of bar lines as we now use them, but by different groupings of the notes, the time value of each depending on its relative position to the others. Perhaps of all forms produced by this system, the _Organum Purum_ was the earliest and most peculiar. It consisted of a _Cantus Firmus_ set to words, and metrical in form; a second voice freely extemporized a higher part, evidently the only rule being that the two finish together. At a late date, strict Discant sometimes alternated with the old Organum, making it much less free in character. =The Important Forms=.—In reality, the important forms produced were entirely in strict metrical divisions. Of these, the most important were the so-called strict Organum, the Conductus, the Roundel and the Motet. Of the strict Organum very little is known, excepting that it was a strictly metrical form, differing, in that sense only, from the Organum Purum; it had also words for all parts and not only for the Cantus Firmus, as had the older forms. The Conductus, from the Latin _conducere_, to conduct, was important, and was a secular form having as its basis a popular melody or a newly invented one, secular words and much freer intervals than church compositions. Each part was expected to be melodious; and it varied from two to four in the number of voices used. It was sung during a march, a funeral cortège or procession. [Music] Conductus for three voices showing that each part is a distinct melody. Oxford History of Music, Vol. I.