Accordingly is the compound time of two dotted crotchets divided by three quavers; is that of three dotted crotchets : y of four. When the division by three is only local, triplets are used. Triplets are groups of three equal notes crowded into the time of two.
Binary and ternary subdivision answers every ordinary pur pose of musical rhythm, being capable of expressing distinctions far more subtle than have ever been regulated in speech. It is impossible to pronounce a syllable in less than a tenth of a sec ond ; but it is easy to play 16 notes in a second on the pianoforte. In such rapid notes a single break twice in a second would have an effect directly measured by the ear. If the broken series were levelled into an even series of fourteen notes a second, the rhythmic effect would be appreciably different, though the actual difference of pace would be only of a second.
The special sign for triplets is readily adapted to other sub divisions. In most cases such adaptation is not meant to produce abstruse rhythms, but to secure an effect of free declamation. Freedom is as necessary in music as it is in speech; but fine play ing, whether in obvious tempo rubato or in apparent strictness, bases this freedom on the superlative accuracy of good rhythmic notation.
The sense of tempo is a larger aspect of the body-rhythm, and in classical music it is very steady. A fundamental law of all musical rhythm is that a hurrying or slackening of tempo has no power to alter the rhythmic organization. If your phrase is too short a ritardando will not make it aesthetically any the longer nor will an accelerando get rid of a redundant bar. On the con trary, it is crowded detail that will best profit by slackening, and loose-knit passages that have most to gain by an unobtrusive mending of the pace.
The genuine tempo rubato is, as its name implies, a rhythmic robbing of Peter to pay Paul. Chopin said that his left hand conducted in strict time while his right declaimed freely. The truth is that sound is as full of illusions as sight. One such illusion has already been illustrated by the grace-notes of Ex. 1, and other illusions are of much the same kind. The tick of metronome measures average time-intervals ; and if it is set to measure a naturally rhythmic performance it will seem to hustle the player in some passages and to drag upon him in others, however care fully we select its pace.
In the classics from Bach to Brahms a movement may give more legitimate scope for tempo rubato than some purists care to admit, but it will not drift from one tempo to a radically dif ferent tempo, unless towards the end, or as evidence of imminent break-up. The gradual drift from one tempo to another first be comes something better than a weakness when the whole nature of musical movement becomes capable of continuity over hours, as in Wagnerian opera. Then, and not before, can we view one and the same tempo from opposite directions. Thus, in Tristan
and Isolde the last part of the love-duet in the second act is a quick movement in time. Isolde's Liebestod ends the opera with an exact recapitulation of this (differing only in the voice part and absolutely unaltered in the orchestra) in rather slow 4 time. By metronome the two tempi should be identical, though the impulse in the duet is energetic and that of the Liebestod reposeful. Wagner merely feels that the broader nota tion better suits Isolde's dying vision; and the listener, who may know and care nothing about the notation, agrees with Wagner.
It is partly a question of accent and comes under the heading of phrasing.
4. The Rhythm of Classical Music in Relation to Poetry. —We can now return, furnished with new criteria, to the relation between musical and poetic rhythm. Even a simple musical set ting of poetry will stretch the words in ways which speech does not normally admit. The naïve poet will unhesitatingly accept this as in the nature of singing. Only the half-baked musical litterateur objects, when Mozart makes Ottavio sing Dana sua pace la mia dipende (Ex. 2) five times as slowly as any speaker could naturally utter the words, and then puts the top note and chief accent on the unimportant la. The poet would be glad to sing it that way if he could. It is quite good Italian prosody to give a nearly equal stress to la and mia: and the climax on la is more than counterbalanced by the fact that the important word mia falls on a harmonically sensitive note. The grammatical sense might have been clearer if a similar but slighter emphasis had been given to sue. But Ottavio is not giving instructions to a servant, but expressing his inmost feelings in solitude. Language does not base its emotional accents on logical analysis. Dr. Johnson corrected a clergyman for saying "Thou shalt not steal" instead of "Thou shalt not steal." If Johnson was right, how in the world did "shall not" ever become "shan't"? The sensitive note on mia shows one of the four main degrees of freedom in musical accent. There is first the normal time-accent. Many critics of musical declamation seem to know no other forms of stress ; but it can be completely eclipsed by putting the highest note of the melody elsewhere. The highest note can in its turn be eclipsed by the longest note. And in Ex. 2, both together are eclipsed by the most sensitive note. Moreover, and without re course to anything so drastic as syncopation, the weakest note in the phrase may be given a special accent stronger than a main beat. This is beautifully shown in the third bar of Ex. 1, where the accented Do, normally quite the weakest note in the bar, could certainly bear the chief syllable in a sentence if words for Haydn's wonderful rhythm could be found at all. Lastly, such a displaced accent may have a double meaning, the note retaining its original lightness in spite of its borrowed stress. Weber has been blamed for his bad declamation in the following famous pas sage:— But, by your leave, this is a triumph of musical gesture. The lively Aennchen might even point a playful finger at the anxious Agathe with each false accent that Weber so explicitly marks. Meanwhile the orchestra corrects the declamation in waltz-rhythm.