But while in poetry the structure of verse serves only to reduce to artistic order the external accidents of expression by language, rhythm is not only the external measure of time in music, but it belongs to the innermost nature of its power of expression, giving to music its distinctive character. There is, therefore, a finer and much more various culture of rhythm necessary in music than in poetry. Here rhythm determines not only the time, how long a note is to be maintained, and how many notes fall within a certain space of time, but it also distinguishes those notes which are to be sung with more or less emphasis. We know that in a bar of 2/4 time the first beat must be more accented than the second; in a bar of 4/4 time the rhythmical accent falls upon the first and third beats; in a bar of 3/4 and 3/8 time only upon the first; and in 6/8 upon the first and fourth. This rhythmical accentuation must become a second nature to the learner before he can express any particular sentiment in a piece of music, and therefore he must be early practised in it. Rhythmical accentuation can always be employed very differently according to the character (_Stimmung_) of a composition, and the most different effects in expression are thus produced. One can, by a greater or less degree of strength, or by a sudden impulse of the breath, change the accent, as well as by a slight retardation of the note. Also, by transferring the accent to those notes naturally not accented, that is, in the 2/4 time to the second beat, or to the second half of the first, by so-called _syncopes_, the whole character of a piece is changed. In musical passages in which many notes come upon one beat and the character of which is light and pleasing, a peculiar charm is produced when several rhythmical accents are made upon the same beat, and likewise in slow passages the swelling of the tone upon the accented note is very pleasing. Let the same phrase in a song be sung with different rhythmical accents, and we may easily see how such changes will give the passage quite another character. The old Italian singers understood to a remarkable degree the use of rhythm in the execution of vocal music. But the poetical rhythm of the words accompanying the voice gives to the singer a guide, reference to which shows him at least how and where he may employ the nicer shades of musical rhythm. CORRECT UNDERSTANDING OF THE TEMPO