§ 81. The variety caused by the different kinds of caesura in the structure of the metres of equal measures, formed on the principle of a regular alternation of unaccented and accented syllables, is much increased by other causes arising from the different nature of Romanic and Germanic versification. These variations came into existence, partly because the poets, in the early days of the employment of equal-measured rhythms, found it difficult, owing to want of practice, to secure the exact coincidence of the word-accent and the metrical accent, partly because for linguistic or (in the case of the later poets) for artistic reasons they considered it unnecessary to do so. They therefore either simply suffered the discord between the two kinds of accentuation to remain, or, in order to avoid it, permitted themselves licences that did violence either to the rhythmic laws of the verse itself, or to the customary pronunciation of the words as regards the value of syllables (i.e. their being elided or fully sounded) or word-accent.
The changes which the equal-measured rhythms have undergone and still undergo from the causes mentioned thus have relation partly to the rhythmic structure of the verse itself, partly to the value of syllables, and partly to the word-accent. From these three points of view we shall first consider the iambic equal-measured rhythm in general (this being the only species used in Middle English, and the one which in Modern English is of most frequent occurrence and influences all the rest), before we proceed to examine its individual varieties.
CHAPTER VI
VERSE-RHYTHM
§ 82. As in Greek and Latin metre, so also in the equal-measured rhythms of Middle and Modern English, it is a general law that the beginning or end of a metrical foot should, so far as possible, not coincide with the beginning or end of a word, but should occur in the middle, so that the individual feet may be more closely connected with each other. When this law is not observed, there arises what is technically called diaeresis, that is to say, the breaking up of the line into separate portions, which as a rule renders the verse inharmonious. On this account lines composed entirely of monosyllables are to be avoided. This law is more frequently neglected in Modern English poetry than in that of earlier times, because the rarity of inflexional endings makes its constant observance difficult.
Even in Middle English poems, however, we often find lines, especially if they are short, which are composed of monosyllabic words only.
These observations may be illustrated by the following examples:
(a) Lines with diaeresis:
Ne ís no quéne so stárk ne stóur.