[§ 675]. Rhythm.—The character of a metre is marked and prominent in proportion as the metrical and the grammatical
combinations coincide. The extent to which the measure a x x is the basis of the stanza last quoted is concealed by the antagonism of the metre and the construction. If it were not for the axiom, that every metre is to be considered uniform until there is proof to the contrary, the lines might be divided thus:—
a x, x a, x x a, x x a,
a x, x a x, x a x, x a,
a x, x a, x x a, x x a,
a x, x a x, x a x, x a.
The variety which arises in versification from the different degrees of the coincidence and non-coincidence between the metrical and grammatical combinations may be called rhythm.
[§ 676]. Constant and inconstant parts of a rhythm.—See [§ 636]. Of the three parts or elements of a rhyme, the vowel and the part which follows the vowel are constant, i.e., they cannot be changed without changing or destroying the rhyme. In told and bold, plunder, blunder, both the o or u on one side, and the -ld or -nder on the other are immutable.
Of the three parts, or elements, of a rhyme the part which precedes the vowel is inconstant, i.e, it must be changed in order to effect the rhyme. Thus, old and old, told and told, bold and bold, do not rhyme with each other; although old, bold, told, scold, &c. do.
Rule 1. In two or more syllables that rhyme with each other, neither the vowel nor the sounds which follow it can be different.