In the study of the Roman Catholic liturgy its alliance with music must be kept constantly in mind, for in inception and in development it was and always has been a musical liturgy. In working out the problems of securing the desired uniformity in respect to musical settings for different localities and of handing down to succeeding generations the musical forms that had gained the sanction of church authority, the church fathers were confronted with difficulties the magnitude of which it is not easy for us to comprehend. It was not until the eleventh century that a system of staff notation was devised whereby the exact pitch of notes could be accurately represented, and a full century elapsed after this vital invention before an adequate system of measured music was evolved whereby the exact relative duration of notes could be represented. A detailed account of the slow and laborious development of the elementary material out of which the fair edifice of modern music was finally to be reared will be found in Vol. I of this series. It will suffice here to say that the authorized versions of the various chants, as the liturgy was gradually taking definite and final shape during the fourth, fifth, and sixth centuries, had to be taught and preserved by ‘word of mouth,’ this process being somewhat aided, through visual association, by means of a kind of musical shorthand called ‘neumes,’ consisting of dots, short lines and combinations of lines written over the syllables to be sung, which indicated the general direction of the melody but not the exact intervals between its tones as it fluctuated up and down in pitch. Even this crude system of representing pitch relations by visual symbols was of great assistance to the singers, for in principle it sought to serve the same purpose that our modern notation accomplishes in suggesting to the eve the outline of the melody. Indefinite as it was in not indicating exact intervallic relations, it greatly aided in recalling to mind the melodies already memorized, assistance which was greatly appreciated by the singers, for as many as a thousand different melodies were used during the church year, many of them for a single occasion only.