B. The invention of the terza rima
Every line of the Commedia is a hendecasyllable, that is, it has (must have) eleven syllables, with the exception of a small number of lines where the final word is a parola tronca (“truncated word”), with an accent on the final syllable (here the line will have ten syllables), or a parola sdrucciola (“slippery word”), with an accent on the antepenultimate syllable (and here the line will have twelve syllables). Both these exceptions are used very sparingly. In the 14,233 lines of the poem there are 32 ten-syllable lines, for example, Purgatorio 4, l. 72 (asterisks mark the accentuated syllables): che mal non se*ppe carreggiar* Fetòn*; and just 17 twelve-syllable lines, for example, Inferno 24, 66: a parole formar* disconvene*vole. These ten-syllable and twelve-syllable lines are still technically hendecasyllables (see below).
Lines which appear to have more than eleven syllables, as many of them do at first glance, prove to have exactly eleven when the principles of what can loosely be called elision (the technical term is synaloepha) are taken into account. Synaloepha is mandatory between vowels across word divisions, except in certain specific circumstances. Thus the phrase selva oscura has four syllables, not five: sel1va_o2scu3ra4, even though the metrical calculation does not affect the pronunciation of the words (both the a of selva and the o of oscura are phonetically fully articulated when the line is read aloud). Elision in the normal English sense, where a sound is suppressed, is always indicated by an apostrophe, as in la notte ch’i’ passai con tanta pieta, where che io is elided to become ch’i’. Dante’s use of synaloepha is one of the most telling aspects of his metrical mastery. Thus a line like biondo era e bello e di gentile aspetto has four cases of synaloepha, meaning that fifteen syllables scan as eleven.
Accentual stresses in the line are also crucial. There must always be a stress on the tenth syllable—this is the fundamental rule. (This rule accounts for the admissibility of the ten- and twelve-syllable lines described in the first paragraph.) There will be a second stress on either the sixth or the fourth syllable, and where the second stress is on the fourth syllable, there will be another stress on the seventh or eighth syllable.
These “three canonical patterns” as they are sometimes called (6-10; 4-7-10; 4-8-10) account for over 99.7 per cent of the 14,233 lines of the poem. There is only a tiny handful of exceptions. (Dante scholars continue to debate how these apparently anomalous lines are to be read.) We do not know Dante’s views on the stresses on the sixth or fourth syllable, and we cannot even be certain that he thought in terms of three basic types of hendecasyllable. The types were theorised only in the sixteenth century in Prose della volgar lingua by Pietro Bembo, who based his analysis on Petrarch’s much more regular metrical practice.
In accordance with the principles just described, almost every line of the poem will fall naturally into two halves: a slightly longer half followed by a slightly shorter half (the 6-10 pattern, conventionally termed a maiore), or a slightly shorter half followed by a slightly longer half (4-7-10 or 4-8-10, conventionally termed a minore). There will usually be a slight natural sense pause, or caesura, separating the two halves.
The hendecasyllable is thus fundamentally different in its governing principles and its rhythmic structure from the English iambic pentameter which it superficially resembles in length. Compare Gray’s Elegy Written in a Country Churchyard as a classic example of iambic pentameter:
The curfew tolls the knell of parting day,
The lowing herd wind slowly o’er the lea,
The ploughman homeward plods his weary way,
And leaves the world to darkness and to me.
The first two lines of the Commedia illustrate the a maiore and a minore patterns (the asterisks mark the accented syllables):
Nel mezzo del cammin* // di nostra vi*ta [6-10]
mi ritrovai* // per una sel*va_oscu*ra. [4-8-10]
(Diphthongs like the -ai of ritrovai are normally elided and count as one syllable.) The seemingly endless and effortless variety of modulation and rhythmic effect Dante produces within this tightly controlled scheme is one of the miracles of the poem.
The entire text of the Commedia marked up for metrical analysis can be consulted online at www.dantecommedia.it, by going to the Collation for any manuscript, then clicking on Metre.
We can only speculate about how Dante came to invent the terza rima. Two generations before Dante, Giacomo da Lentini, an Italian poet working at the court of Frederick II in Palermo, invented the sonnet, and the form immediately became popular. The structure of the sonnet as it was used by Italian poets up to and beyond Petrarch and the Renaissance consists of a pair of quatrains (the octave) followed by a pair of tercets (the sestet). One set of rhyme sounds is used in the quatrains (commonly in the pattern abba or abab, repeated); a new set is introduced in the tercets. The varying possibilities for the arrangement of the rhymes in the tercets allows for an element of experiment and subtle variation, which Dante and his contemporary poets exploited to the full. Here are the patterns used by Cavalcanti and Dante in their sonnets: cdc cdc; cde cde; cde edc; cdc cdd; cdd dcc; cde dce; cdc dcd. The last one is already potentially close to the terza rima.
Shakespeare’s sonnets, more familiar to English readers, crucially alter this structure, replacing two quatrains and two tercets [4 + 4 + 3 + 3] with three quatrains and a couplet [4 + 4 + 4 + 2]. This structure, with its clinching couplet, feels very different in both its organisation and its rhythm.
A plausible explanation for Dante’s invention of the terza rima sees it as a fruitful cross between the tercet of the sonnet and the four-line metrical unit of the serventese, a more extended verse form which had been imported into Italy from Provence. The serventese was commonly used for narrative, discursive, and satirical rather than lyric poems. One form of the serventese popular in Italy used a four-line unit with a relatively undemanding rhyme scheme (aaab bbbc), where a shorter fourth line created a link through rhyme to the following unit. Against the sonnet’s mandatory fourteen lines the serventese could be as long as the poet pleased. Dante certainly wrote at least one serventese, though it no longer survives. It was a poem, he tells us in the Vita Nova, in which he listed the names of all the attractive young ladies in Florence, and in which, no matter how he rearranged the material, Beatrice’s name always ended up in ninth position. Nine is of course three times three, and thus doubly significant as Beatrice’s number.
Dante wrote many sonnets, and he may have written a sonnet sequence. If, as many people believe, he is the author of Il fiore (“The Flower”)—a late-thirteenth-century Italian translation of the Roman de la Rose into a sonnet sequence—then he had worked with the tercet as an element in an extended narrative structure, albeit still embedded within the sonnet form. The sonnets of the Fiore all follow the pattern cdc dcd in their tercets, with no variation or experimentation at all: this pattern, as noted above, is already potentially close to the terza rima. All that remained to do was to eliminate the quatrains, liberate the tercets from the larger metrical structure, and devise the linking rhyme scheme.