The amplification which he made in the Ambrosian scale was the addition of four tones or plagal modes, and also that he totally abolished the difficult Greek nomenclature, such as para-mese and proslambanomenos, and gave the names of the first seven letters of the Roman alphabet, to the seven notes, A, B, C, D, E, F, G, in the same manner as used to-day. There is no question but that the scale founded by Gregory, had a diatonic character, but as to the number of systems of tones employed, authorities differ, and even the books of music of Gregory’s own compilation (one of which was chained to the altar at St. Peters, to fix the standard of tone for ever and ever) do not clear up the difficulty, for the number differs.
But the system gradually settled itself, and eight tones only (our ordinary diatonic scale tones) were found practicable for composition and singing.
Gregory’s system was founded on the division of the octave into two intervals; a perfect fifth and perfect fourth. The fifth was, next to the octave, the most important interval.
The added modes (called plagal, signifying “oblique, sideways”), were so called to distinguish them from the authentic tones or keys (D, E, F, G, A), a synopsis of the entire set of tones would be as follows,—
| A, | B, | C, | D, | E, | F, | G, | A, | B, | C, | D, |
| plagal 4, | ||||||||||
| authentic 5, | ||||||||||
| plagal 4. | ||||||||||
There were four authentic modes, viz.,—D, E, F and G, and four plagal, as follows,—A, B, C and D.
To give a description that would be at all adequate, of the system of Gregory, would require much space, and many plates and engravings. We shall therefore touch but lightly on the tone systems and notations of the early and middle ages. The founding of the scale from a fifth and fourth, led to one grave mistake; these intervals were supposed to be of prime importance, and more perfect than others, and finally were employed in harmonies which were decidedly harsh. But to such an extent did the evil spread that no composition (in the dark ages) was thought to be pure or classic, without containing a series of fourths, fifths, and octaves, and an invariable close upon an empty fifth. Thirds were rejected as totally impure. But these faults are not of Gregory’s origination, and he must ever stand as the man who made the connecting link between the old Greek music and our own.
CHAPTER XXII.
MUSIC IN EUROPE FROM THE FIFTH CENTURY.
In proceeding to briefly sketch the curious facts of musical history in the dark ages, we shall necessarily confine ourselves to pointing out only what is chiefly remarkable, and shall not enter into the field of dispute regarding systems and notations, for this period of Musical History is a very hazy one. It is but natural to suppose, that when general barbarism spread over Europe, music was not likely to be either much practised or written about. The last writer on the previous systems was Boethius (the last of old Roman writers), who lived at about the same epoch as Gregory (he was put to death by Theodoric, the Goth, A. D. 525).
In his work, he uses the letters of the alphabet, to designate musical notes, but does not repeat the letters at the octave; his nomenclature therefore does not end at G, but continues on, to N, O, and P.[256]