22. Next to equivalence, the most important and valuable engine in the constitution of English verses is the variation of the middle or internal pause.
Practically at discretion.
23. Except in very long lines—which always tend to pause themselves either at the middle or at two places more or less equidistant—there is no reason why the pause of an English line should not be at any syllable from the first to the penultimate, and none why it should or should not occur at the end of a line, couplet, or even stanza—though in the last-named case rather special reasons are required for its omission. Not every line need necessarily have any pause at all.
Blank verse specially dependent on pause.
24. The effect of blank verse depends more upon pause-variation than upon anything else; and by this variation, accompanied by stop or overrun ("enjambment") at the end of the line, verse-paragraphs are constituted, which can contain verse-clauses or sentences, in like manner brought into existence by pauses.
§ E. Line-Combination
Simple or complex.
25. Lines, composed as above of feet, can be used in English either continuously on the same or equivalent patterns, or in batches of two or more.
Rhymes necessary to couplet.
26. The batches of two almost necessarily require rhyme to indicate and isolate them, especially if the individual lines are of the same length. Other batches [stanzas] might, as far as any a priori objection goes, consist of unrhymed lines, symmetrically correspondent, or irregular [Pindaric].