De nuptiis Philologiae et Mercurii, Book III (De arte grammatica), part 2 of 4 (about §§ 263-287)
When Grammar had said this, and Jupiter and the Delian god bade her proceed, Pallas said: “While Literature hurries over these things, she has passed over the historical part concerning the joining of syllables.” Alarmed by this reproach of the maiden, she said: “I know that I must pass over very many things, lest by linking the smaller points I incur the weariness of the heavenly blessedness. Therefore, with the matter set before me, I shall hasten through the short paths, lest, overshadowed by dense branches, I grow wild as it were with the thickness of a thorny abundance. A syllable, then, is so called because it is formed by letters joined together and taking a sound at the same time. Of it, as I have said, there is no doubt that there are three parts: concerning the joining, concerning the pitch, and concerning the lengths. Of joining there are four kinds, two natural and two historical. The natural are when it is asked of each syllable whether it is joined from one letter or from two. When letters cannot be joined together, another letter is added and they are associated, as M and N, which, since they do not unite, are associated by the approach of a vowel, as in amni and somno; and these kinds of joining are passed over, because they were mentioned in the discussion of the letters. The historical joining, however, is when, out of letters which can be joined with one another, the diversity of speech does not associate the same ones nor an equal number. For we write the first syllable of Musae with two letters, the Greeks with three. Lucilius in the dative case joins A and E, saying Terentiae, Orbiliae [Licinius], and A and I; and Lucretius often, and our Maro, aurai, pictai. Likewise there are two joinings when we unite syllables for the sake of the foot or the verse, so that two suddenly perish in one, as in synaloepha, or when letters are cast out of a word, as in ecthlipsis.
Thus far on joinings. Now let us look at the pitch, a topic which among the Greeks is called peri prosodion. This is divided into three. Every syllable is either grave or acute or circumflex, and as no [voice] is without a vowel, so none is without an accent. And the accent is, as some have thought, the soul of the voice and the seedbed of music, because all modulation is composed of the heights of the voices and of gravity, and therefore the accent is called, as it were, adcantus. Every Latin word, simple or compound, has one sound, either acute or circumflex. It can never have two acutes or circumflexes, but it often has a grave. It has the acute on the first syllable if you say Caelius, on the second in Sallustius, on the third in Curiatius; the circumflex likewise on the first if you say caelum; but the syllable nearly last is never sharpened by nature itself, but the one preceding it, that is, the third from the last, whether it be short or long, as Cicero, Caelius. The circumflexed sound rests only on the syllable which precedes the last, and only if it is itself long by nature and the last is short, as Galenus. But if the last is long, or if the next to last is long by position though the last is short, the sound will nevertheless be acute, as Galeni, Camilli. It is a peculiarity of the circumflex that it attaches only to syllables long by nature, whereas the acute is found on both long and short. Every word must have either an acute or a circumflex sound, even if it is a monosyllable. For monosyllables lack the grave. Every monosyllabic word, when it signifies something, whether it is short or long by position, will be sharpened, as we say far, ars. If it is long by nature, it will be circumflexed, as lux, mos. Disyllables sharpen the former syllable, either when both are short, as citus, or when both are long by position, as sollers, or when either is long by position, as cohors. But if the first syllable is long by nature and the following short, the first will be circumflexed, as luna; if the latter is long by position or nature, the first will be sharpened, as codex, docte. For no long syllable will be found grave if it is the first in a disyllable. In trisyllables, if the middle, which we call nearly last, is short, it is certainly pronounced with the grave accent, and at once the first of them, that is, the third from the last, will be sharpened, as in Cotulus; but if the same is long, it matters how it is long. For if it is long by nature and the last short, the middle is circumflexed, as Cethegus, Mancinus; but if the middle is long by nature and the last long too, the middle will be sharpened, as Catoni, Ciceroni; or if the middle is long by position, the acute will remain whatever the last may be, as Catullus, Catullo, Metellus, Metello. The pronouns which are declined in two ways, that is, either shortened or lengthened, sharpen the middle syllable in the genitive case, ipsius, illius. If the seconds of these are made short, the firsts will be acute, as ipsius, illius. But if the middles are long, the firsts will be grave and the seconds circumflexed, as in the verse about the sun setting and the one about a man killed. Therefore the firsts are acute when the middles are short; when the middles are long, they are acute or circumflexed: acute when the last are long, as tenebrae, latebrae, maniplos. These differ from the above [which are others, like Catullus, Sallustius] in this, that those have separate consonants, while these, although they too have the nearly last syllable long by position, yet keep no consonants in the second syllable, but there are two in the third. And so it came about that these nouns, tenebras and latebras, bore the sharp accent on the first syllable, but maniplos and fenestras were said with the acute on the nearly last syllable. Some thought that kind of nearly last syllable to be entirely short, because it was not ended by a consonant; others, because, though not ended by a consonant, the next syllable began with two consonants, and because the nature of the letters L and R, being soft, makes a syllable now long, now short. No Roman word of two or more syllables ends in an acute sound, and the circumflex is never final except where the latter part runs out into a syllable long by nature, as ergo and pone.
The context of speech often takes away or changes the proper sounds of single words. It takes them away from those which refer to something following, as prepositions: ante urbem. For here ante has lost the acute sound of the first syllable. Likewise post muros. Accents are changed by the joined words que, ve, ne, when que is a copulative conjunction, ve an expletive, as in the phrases “You wish Latium to grow” and “and goads my heart,” in Accius in the Pelopidae. The acute sound has never migrated from the first syllables to the last, except in the joined particles, whose peculiarity it is to sharpen the last parts of the words to which they are joined. Greek names, when they are turned into Latin, are pronounced by our rule unless they remain Greek. Olympus, therefore, and Caucasus are pronounced as Latin words, and it is clear which syllable they ought to sharpen or circumflex according to the rule written above. But if they remain Greek and we follow this rule in foreign words, it is nevertheless necessary that in the oblique cases they keep the acute sounds on the middle syllables, since among the Greeks too we hear them uttered with no other accent. The acute accent is marked by a little stroke rising from left to right; the grave, descending from left to right. The sign of the circumflex is a sigma curved over the letters themselves. The accents we call partly fastigia, because they are placed on the heads of the letters, partly peaks, tones or sounds; the Greeks, prosodiai. It should be known also that all three accents can attach to a single word, as in Argiletum.
I think it has been fittingly said what the pitches of syllables are and how they are changed. Now I shall set out their lengths. Every syllable is either short or long or common. It is short when the vowel is shortened and helped by no following letters, or when the form, once shortened, is ended by a letter. It is long in two ways, by nature and by position. By nature: when the vowel is lengthened, or when the syllable holds a circumflex accent [or an acute on the nearly last], or when it is a monosyllable [each vowel being one], or when a diphthong is found, or when the first syllable, compounded under another form in any word, changes neither the vowel nor the accent. By position: when two consonants follow a short vowel, whether in the same syllable or in the next, or divided between both, or three in one, or one double. The double letters are X and Z; sometimes I and C can become so, as if I is between vowels, as in aio, Troia; likewise C, as in the line “this was the nurturing mother.” These forms of consonants or double letters help the short ones only if they are enclosed in the same word. For the consonants of the next word do not help the preceding one, although Virgil objects, saying, “I sing of arms and the man of Troy,” and likewise, “and I call the springs and rivers.” The diphthongs are AE, OE, EV, AV, EI. Apart from these [syllables] no diphthong is mentioned.
Of common syllables there are eight ways. The first is when a liquid placed beneath the consonants follows a shortened vowel; for it is long in “in the vast cave of the Cyclops,” short in “and the vast Cyclopes from the rock.” The second way is when a shortened vowel ends in one consonant and H follows; for it is long in “we weary their backs with the spear,” short in “whatever honor of the tomb.” The third is when two consonants follow a shortened vowel, of which the first is the letter S; for it is long in “whence the thick hair,” short in “let each lay down hopes for himself.” The fourth way is when a short syllable ends a part of speech; for it is long in a clause, as in “for to you, Tiber, Evander’s head,” short in “this head, citizens.” Likewise another place: it becomes common from a diphthong, long as in “Muses of Aonia,” short as in “the islands in the great Ionian.” For when a vowel follows, a diphthong can become short, as in “with stakes burnt at the tips.” Another place is when another vowel follows a long vowel; for it is long in “I, unhappy, whom you flee,” short in “beneath lofty Ilium.” Another place, when a pronoun is ended by the letter C and a vowel follows; for it is long in “this was the nurturing mother,” short in “this alone turned the sense.” Another place, when Z follows a shortened vowel; for it is long in “the spoils of the leader Mezentius,” short in “wooded Zacynthos.” Nature has been spoken of in the three kinds of syllables. It remains to speak of the final ones, in which the authority of the art and the canonical form consist. And first the noun must be taken up again.
The nominative singular ending in the letter A is short, as Catilina, Iulia. Ending in E in Greek words it is long, as Euterpe. Ending in I it is long, as frugi. Ending in O it is short in Latin words, as Cato. Ending in V it is short, as cornu. Ending in AL it is short, as tribunal; EL short, as mel; IL short, as vigil, except the one Etruscan name Tanaquil. OL is long, as sol; VL short, as consul. Ending in M it is short, as tectum, although an example of this rarely occurs, because M, caught between vowels, is removed like the harshness of mytacism. Ending in AN it is lengthened, as Titan; EN in neuters is short, as carmen, in other genders long, as lien, siren. Ending in ON it is long, as Memnon. AR ending is long in monosyllables only, as Nar, far. ER ending in Latin words is short, as puer, except the one monosyllable ver; in Greek words it is lengthened, as aer. IR ending is shortened, as vir. OR ending is short, as auctor. VR ending is shortened, as murmur, except the one monosyllable fur. AS ending in Latin nouns is lengthened, as facultas, paupertas; in Greek words it is short only when the genitive ends in -DOS, as Arcas, Arcados. ES ending in Greek nouns is short, as Anchises; in Latin, if it is of the fifth declension, it is lengthened, as dies. If of the third, it is long when the genitive singular does not increase a syllable, as labes, or, increasing, keeps a long E before the last syllable, as quies, quietis. For if it changes it to I, as miles, militis, or shortens it, as seges, segetis, it is shortened, excepting Ceres, pes and the like. IS ending is short, as agilis. OS ending is short in Latin only when the genitive has no naturally long syllable before the last, as os, ossis. In Greek words it is shortened when the genitive ends in a diphthong, as Delos, genitive Delou. VS ending is short, as doctus, but becomes long if the genitive has grown by a syllable and has a long I or V before the last, as virtus, and in one indeclinable, pus. T ending is shortened, as caput. C ending makes only two nouns, as allec, which is lengthened, and lac, whose declension is doubtful. The genitive singular is lengthened when it is like the nominative, as senatus, or has a diphthong, as Iuliae, or ends in I, as docti; in the rest it is shortened. The dative singular is lengthened, as Pompeio; in Greek words it is shortened if it ends in the letter I, as Palladi. The accusative singular in Greek words is shortened only when it ends in A or ON, as Thesea, Delon, but in Latin it is short, as doctum. The vocative singular ending in the letter A is shortened in all Latin words and in Greek feminines, as tabula, Musa; in masculines it is long, Aenea. E ending in Latin words is short, as docte; in Greek words lengthened, as Tydide, except those whose Greek nominative ends in -os, as Phoebos, Phoebe. I ending in Latin words is long, as Mercuri; in Greek shortened, as Nai. O ending in Latin words is short, as Cato, though Virgil thinks otherwise; in Greek lengthened, as Dido. V ending is shortened, as cornu. Nominatives ending in consonants follow the rule, except Greek names, which are often altered by the variety of languages, as Diomedes. The ablative singular is always lengthened except when it ends in E, only in those nouns which are of the third declension, as a pariete. The nominative and vocative plural in the masculine and feminine genders are lengthened, as fluctus, terrae; in neuters they are short, as fata; in Greek words when they end in S or A, as rhetores, poemata; in others they are long, as Musae. The genitive plural is short, as doctorum; in Greek long, but in Greek declension, as Phaeacon. The dative plural and ablative, if ending in -IS, are lengthened, as doctis; if in -BVS they are shortened, as hominibus. But if the declension is Greek, a dative ending in -IN is shortened, as Arcasin; otherwise it is long. The accusative plural in all masculines and feminines is lengthened, as doctos, Iulias; in neuters it is shortened, as moenia; in Greek words, if it ends in AS and comes from a genitive ending in -os, it is shortened, as Arcadas; otherwise it is lengthened, as Musas.
The nominative singular of all pronouns ending in I is found shortened, except the two monosyllables tu and qui. The genitive singular delivered in I or E is long, as mei, meae; otherwise short, as illius. The dative singular is always lengthened, as nostro, except mihi, tibi, sibi, which are taken either way. The accusative singular is shortened, as illum, except me and te. The vocative singular does not differ from its nominative. The ablative singular is long, as ab illo. The nominative and accusative plural are shortened only when they end in A, as nostra. The genitive plural is never lengthened, as illorum. The dative and ablative plural ending in -IS are lengthened, those ending in -BVS are shortened. In all moods, tenses, numbers, persons and conjugations of the verb this is the uniform rule. Any person ending in A is lengthened, as canta. Ending in E it is short, as lege, unless it comes from the second conjugation, as doce; then it is long. A person ending in I is always lengthened, as nutri. One ending in O is shortened, as audio, though authority differs even in these. For Virgil makes the first person of the first conjugation long, as in “I sing what I was wont” and “to you I commend.” Yet monosyllables too are to be lengthened, as do, sto, fio. A person ending in V is lengthened. One ending in AM is short, as legebam. One ending in OR is shortened, as legor. Verbs ending in the letter S are lengthened: if the next-to-last letter is A or E, as amas, doces, except the monosyllable es and its compounds, as ades. But if I precedes S, it is shortened, as legis, legitis, except the second person of the indicative mood, present tense, singular number, lengthened from the third conjugation, as nutris, audis, and from the verb volo, vis. But if V precedes S, it will be shortened, as nutrimus. Those ending in the letter T are shortened, as legit. Those ending in C are lengthened, as produc. Participles, though they are inflected through the cases, nevertheless differ from nouns in every way. Monosyllabic adverbs, as huc, or those which are made from them, as illuc, are all lengthened, except bis and ter. Those ending in A are long, as una. Those ending in E are lengthened, as docte, pulchre, except those which are either not compared, as rite, or are defective in comparison, as bene, impune. Those ending in I are long, as heri, except ibi and ubi and those compounded of them, as sicubi, likewise quasi. Those ending in O, if derived from themselves, are short; if led from others they are lengthened, as falso, though authority varies. Those ending in V are long, as noctu. Those ending in L ought to be shortened, as semel. Those ending in M, N, R are short, as cursim, forsan, fortiter. Those ending in S are lengthened only when A precedes it. Those ending in C are lengthened, as illuc.
In all participles of the future tense the nominative singular is short, as lecturus; the genitive and dative singular are lengthened, as lecturi, lecturo, except the participle of the present tense, which shortens the genitive, as amantis. The accusative and vocative are agreed to be short, as lecturum, lecture; the ablative singular is shortened only, as amante, legente. The nominative and accusative plural in participles of masculine or feminine gender are lengthened, as lecturi, lecturos; in neuters they are shortened, as lectura. The genitive plural is short, as lectorum. The dative and ablative plural ending in -IS are lengthened, those ending in -BVS are shortened. The copulative, disjunctive and expletive conjunctions are short, unless position has made them long. Of the causal and rational ones, those ending in A, except ita and quia, are lengthened, as propterea, interea. Those ending in I, except one, are lengthened, as si. Those ending in N, if they have I before it, are lengthened, as sin; otherwise they are short. All the rest are agreed to be shortened.
The prepositions which end in A alone glory in lengthening, as contra and extra, and the one monosyllable a. The ablative prepositions are all shortened, except monosyllables which either consist of vowels or end in vowels, as e and de. Prepositions of both cases are undoubtedly shortened. Interjections are long if they are monosyllables, as heus; if they are disyllables or trisyllables, since they keep the aspect of parts of speech, they are to be judged by the example of those they resemble, as papae. These things, as I have said, must be observed in the final syllables through all the parts of speech, except those long by position and diphthongs.