In order to gain an insight into and an ap preciation of the nature and character of the Gregorian melodies, it will be well to examine a little more closely the tonal material out of which they are constructed. We will notice that all the scales are diatonic, that is to say that each one has five whole tones or steps and two half-steps or semi-tones; furthermore that the half-steps or semi-tones occur in a different place in each scale, according to what the initial note happens to be, and, finally that only one of them has a leading tone or half-step between the seventh step and the octave or repetition of the initial note. It is these three features which differentiate the Gregorian modes so markedly from our modern scales and which give them that impersonal and objective character so mar velously suited to the purpose they serve, namely, that of expressing the ideas and senti ments conveyed by the sacred texts. In other words, these modes, or tonalities, lend them selves to the expression of a mental attitude of objectivity as against the modern scales which, on account of their chromatic character, are more pliable vehicles for conveying the emotions springing from subjectivism and introspection. If we remember, in addition to the general char acter of the Gregorian, or Church modes — as they are often called— the rule which permits the use of six intervals only in the formation of Gregorian melodies, namely: the major and minor second, the major and minor third, the Four more modes were added to these in later centuries, but they are not different in essence from the eight named above. By means of various signs — dots, strokes, bars or hooks, collectively called neums — all of which had a conventional meaning, and which were placed over and alongside the words of the texts, Saint Gregory indicated the melodies to which these texts were to be sung. The book containing the perfect fourth and the perfect fifth, we realize that this tonal system is better adapted for the expression of reverence, humiliy, peace and joy, whereas the modern chromatic system is more suited for the expression of passion and dramatic conflict.
Saint Gregory used every means at his com mand to propagate the chant and have it uni versally adopted. He established schools for its proper interpretation. At one of these he is said to have taught in person. Missionaries who were sent from Rome into foreign lands took with them a copy of the antiphonarium, and, of course, a knowledge of how the melo dies it contained should be sung. Thus, Saint Augustine brought the melodies to England at the command of Saint Gregory himself. The great pope's successors continued the process of propaganda during the following centuries. In the 8th century Saint Boniface introduced the chant in Germany, and by him several cantortun" were established on German soil. Through Pepin and after him through Charle magne, it found its way into Gaul and into the whole territory under the emperor's sway.
It is held by many historians that the origi nal chant was, in the main, syllabic, that is to say, that only one note was sung to each syl lable and that only the word was ever extended over several notes. Be that as it may, it is certain that it gradually developed into a melismatic system, syllables being often ex tended over smaller and greater groups of notes.
From the time of Saint Gregory until the ad vent of Guido d'Arezzo (995-1050?) the primi tive means of determining the melody, the neums described above, remained in use. As has been pointed out, these signs were intended to assist the memory of the singers in repro ducing the melodies which they had learned by oral transmission. It is not to be wondered at
that, in the course of time, many of the melo dies were altered and modified in the many places where they were in use. There were fre quent variations and modifications due to local habits, different temperaments, but above all, to the insufficiency of the means employed to indi cate with precision the form of the melodies. Careless copyists and finally the arbitrariness and caprice of singers in the various countries led to confusion. Before the time of Guido d'Arezzo, attempts had been made to fix with more precision the intervals of the melodies. He found in use two lines, a red and a yellow one, drawn across the page. Upon the red line was placed the F, and C was put upon the yel low one. Above, below and between these two lines the neums were written. By placing a black line between the two already existing and adding another above or below these three as the ambitus or range of the melody might re quire, Guido created the four line staff which has been used ever since for the chant, and made it possible to indicate precisely the form of a melody for all time to come. Guido and his pupils transcribed the existing chants into the new system of notation. Copies of these transcriptions found their way into the cathe drals and monasteries of many countries where they took the place of the books formerly in use. Though the neums as a system at nota tion were superseded by the more precise in vention of Guido, they continued nevertheless to be employed to indicate the manner of interpre tation. Although Guido's invention was epoch making and of incalculable importance in the history of music, it must not be inferred that it was at once universally adopted. Neums as a means of notation continued in use in many places and institutions far into the 13th cen tury. Nor must we imagine that because of the introduction of the new system of notation no further modifications of the chant took place. As new saints were canonized and new feasts instituted by the Church, offices and chants were necessarily created. Then the growing skill of professional singers gave rise, especially in the Alleluja following the gradual, to improvisa tions, elaborations and displays of virtuosity which often exceeded the limits of good taste and appropriateness.
As the melodies comprising ecclesiastical music grew out of the sacred texts and were never performed without being wedded to these texts, it is but natural to assume that the melodic construction partook of the rhythmical form of the texts. Especially must this have been the case when the chant was still largely syllabic. Some maintain that the ancient chant had a definite — artificial — rhythm, as in our modern music, in contradistinction to the nat ural, or that dictated by the rhythm of the text. Whatever the prevailing rhythm was at the beginning of the 10th century, it was now to undergo a gradual change. The monk Huc bald invented the organum or diaphony, that is, the practice of having a second voice sing the melody a fifth above or a fourth below the origi nal, or add to the fifth also the octave, the first voice meantime maintaining the original melody. By this step Hucbald paved the way for the polyphony which was soon to develop and find its culmination in the wonderful creations of Palestrina and his school in the 16th century. Sulzer in his Theorie der in the article on harmony, points out that polyphony was latent in the unison singing of the Gregorian melodies by old and young, men and boys, each class of voice, soprano, alto, tenor, baritone and bass, having a different pitch.