De vulgari eloquentia (II, x, 1-6)

(1) Scientes quia rationale animal homo est, et quia sensibilis anima et corpus est animal, et ignorantes de hac anima, quid ea sit, vel de ipso corpore, perfectam hominis cognitionem habere non possumus; quia cognitionis perfectio uniuscuiusque terminatur ad ultima elementa, sicut Magister Sapientum in principio Physicorum testatur. Igitur ad habendam cantionis cognitionem, quam inhiamus, nunc diffinientia suum diffiniens sub compendio ventilemus; et primo de cantu, deinde de habitudine, et postmodum de carminibus et sillabis percontemur. (1) If we know that a human being is a rational animal, and that an animal consists of a body and a sensitive soul, but do not know what that soul is, nor yet that body, we cannot have a perfect understanding of the human being; for the perfect understanding of anything must take into account its basic elements, as the master of those who know affirms at the beginning of his Physics. Therefore, in order to acquire that understanding of the canzone at which we aim, let us now briefly undertake the definition of the things that define the canzone itself, beginning with its melody, moving on to its organisation, and finally discussing its lines and syllables.
(2) Dicimus ergo quod omnis stantia ad quandam odam recipiendam armonizata est; sed in modis diversificari videntur; quia quedam sunt sub una oda continua usque ad ultimum progressive, hoc est sine iteratione modulationis cuiusquam et sine diesi; et diesim dicimus deductionem vergentem de una oda in aliam (hanc voltam vocamus cum vulgus alloquimur); et huiusmodi stantia usus est fere in omnibus cantionibus suis Arnaldus Danielis, et nos eum secuti sumus cum diximus, Al poco iorno e al gran cerchio d'ombra. (2) I say, then, that every stanza is constructed harmoniously for the purpose of having a particular melody attached to it. But it is clear that stanzas differ in form. For some are accompanied by an uninterrupted melody, in an ordered progression from beginning to end - that is, without any repetition of musical phrases or any diesis (and by diesis I mean a movement from one melody to another, which we call a 'turn' when speaking the vernacular). Stanzas of this kind were used by Arnaut Daniel in nearly all his canzoni, and I followed him when I wrote Al poco giorno a al gran cerchio d'ombra. [To the short day and the great circle of shadow]
(3) Quedam vero sunt diesim patientes; et diesis esse non potest, secundum quod eam appellamus, nisi reiteratio unius ode fiat, vel ante diesim, vel post, vel undique. (3) Some stanzas, on the other hand, tolerate diesis: but there can be no diesis, in the sense in which I use the term, unless one melody be repeated, either before the diesis, or after it, or on either side.
(4) Si ante diesim repetitio fiat, stantiam dicimus habere pedes; et duos habere decet, licet quandoque tres fiant: rarissime tamen. Si repetitio fiat post diesim, tunc dicimus stantiam habere versus. Si ante non fiat repetitio, stantiam dicimus habere frontem; si post non fiat, dicimus habere sirma, sive caudam. (4) If the repetition occurs before the diesis, we say that the stanza has 'feet' [pedes]; and it should have two of these, although cases do occur - albeit very rarely - where it has three. If the repetition comes after the diesis, we say that the stanza has 'verses' [versus]. If there is no repetition before the diesis, we say the stanza has a 'forehead' [frons]; if there is none after, then we say it has a 'tail' [sirma, cauda].
(5) Vide igitur, lector, quanta licentia data sit cantiones poetantibus, et considera cuius rei causa tam largum arbitrium sibi usus asciverit; et si recto calle ratio te duxerit, videbis auctoritatis dignitate sola, quod dicimus esse concessum. (5) So you can see, reader, how much room for manoeuvre is available to those who write canzoni, and you should consider why poetic practice has bestowed such extensive discretionary powers on itself. If reason has guided you along the right path, you will see that what I describe has only come about in recognition of the stature of authoritative models.
(6) Satis hinc innotescere potest, quomodo cantionis ars circa cantus divisionem consistat; et ideo ad habitudinem procedamus. (6) It should now be clear enough what the technique of the canzone has to do with the articulation of the melody; and so let us move on to its organisation.