I'm finally getting around to my very limited response to the brouhaha over Paul Lake's "Enchanted Loom." No sane person thinks that the English 14-line iambic pentameter sonnet, in any of it's common rhyme schemes, is an inevitable product of the course of human evolution. Nevertheless, the sonnet exploits, in its memish way, a number of evolved human characteristics and along the way enlists some of the properties common to all Englishes since the late 14th century. Let me name the ways, in no particular order and with no claim to completeness--this is a blog. Please don't think that I am arguing that the sonnet is the quintessence of the poet's art or anything silly like that. I only want to show that it is equally silly to call the sonnet structure merely conventional.
We like and need rhythm, and it's intimately connected to language. Remember American Bandstand? "I'll give it an 85, Dick. It's got a good beat and you can dance to it." There are various ways to produce rhythm in speech sounds, but the most important are by varying, in an organized way, either the loudness or the length, or both, of a series of syllables. It's also possible to produce a rhythm by clumping isochronous, isostressed units of sound into groups varying in length in some organized way, but there are severe limits on the length of such patterns we can recognize, and the natural stresses of English interfere with that, which is why syllabics don't work well in lines of more than about seven syllables. English has no regularly varying syllable lengths, so we can't reliably organize speech rhythms that way as the way speakers of ancient Greek could. Stress is, practically, all we've got at the level of syllables.1 English sonnets, using an accentual-syllabic meter, have a recognizable rhythm at the lowest level.
It is no accident that the basic rhythmic unit is basically unstressed-stressed rather than stressed/unstressed. In very simple terms (remember this is a blog), before English spent 300 years underground absorbing French, much of the grammatical information about words was carried in inflections at the end of words. We've lost almost all of that and rely much more heavily on syntax and connective words like prepositions, shifting names and actions from the front to the back of phrases, and thus shifting natural speech rhythms. Old English poetry has a trochaic feel2; since the 14th century it's been mostly iambic.
As much as we like rhythm, we get bored when it's too simple or too complex. Judging by folk poetry and song, we like our stresses in 3 or 4 beat groups, and we're more tolerant of variation on the off-beat. This appears to be nearly universal: longer and more complicated patterns do occur in literary poetry and in (there's no good word for it) classically influenced music, but even the astonishing rhythmic virtuosity of jazz occurs almost entirely in a 4/4 framework. Sonnets use pentameter, the longest line frequently used in English, recognizable by even a moderately trained ear and capable of sufficient variation to satisfy all but the most jaded tastes. Shorter lines can tolerate more inconsistencies in the positioning and number of unstressed syllables and still be easily recognized, but the pentameter is long enough to employ a caesura and recognizable levels of stress within the line. The lines themselves can be organized into larger rhythmic groups using enjambment, rhyme, and other means. A poem much longer than the sonnet cannot easily maintain a global rhythmic structure; a poem much shorter can't have varying parts to that structure.
We like speech, and we are really good at recognizing it as speech, even when we can't understand it. We produce phonemes at a rate of about 7 a second, which is just a buzz for most sounds; for unfamiliar languages, it's the reason those other folks seem to talk so fast. It's physically irritating when other speakers don't make sense to us, which, depending on our tolerance and expectations, can lead us to make an effort either to understand or to avoid the speaker. It's also irritating, even insulting, except in the briefest and most casual encounters, when the speech of others is uniformly brief and simple. The sonnet's 14 lines, 140 syllables, are within the comfortable limits for a reasonably clear statement of an idea, an emotion, an argument, or a short narrative, but it isn't so long that its surface structure can't be comprehended in the time it takes to hear or read it.
We like symmetry, but, like rhythm, it shouldn't be either too simple or too complicated, and, within limits, we like being surprised. There are two main kinds of sonnets in English, each of which solves this problem in a different way, which I'll get to Friday (I'm playing mandolin tomorrow night) along with some notes about the intellectual structure of the sonnet. 5:30 comes early, every day.
1Clearly there are other methods of producing rhythm at higher levels such as the phrase or, in poetry, the stanza, and most free verse depends on these other methods.
2I know that it was accentual and that trochaic strictly applies only to quantitative or accentual-syllabic verse. Blog, remember?