Unmetered poetry
Through his description of St Ambrose's hymn Deus creator omnium, St Augustine evidently
had a concept of longs and shorts, measured in a 2:1 ratio, which were part of the definition
not just of poetic feet and metre but also of musical rhythm in general, since music, through
the long and short notes, could imitate without words the patterns of the feet of poetic metre.
In his day, the way in which lines of poetry ended was very regulated.
De musica, book III, chapter I, paragraph 2
English: Gregorian Rhythm in the Gregorian Centuries, Dom Gregory Murray, 1957
What St Augustine is saying here is that classical poetry is founded on fixed rhythmic
schemata called metres that are built out of specific measured patterns of poetic feet (eg,
iamb, trochee, etc). He closes by clarifying that rhythm in general is not always linked to the
fixed patterns of classical metres and that when it is not, it nevertheless remains orderly
through having its own schemata likewise built out of feet which, being made of longs and
shorts, have a structure similar in nature to fixed poetic metres.
St Augustine, De ordine, book, II, chapter XIV
English: Gregorian Rhythm in the Gregorian Centuries, Dom Gregory Murray, 1957
St Augustine therefore distinguishes between i) a measured, regular system in which the long
and short verbal syllables followed the set patterns of feet of poetic metres, which involved
lines ending with specific patterns of feet, and ii) an unmeasured, irregular system in which
metrical feet are used but not ordered after the set patterns of the poetic metres, the lines
being free to end with any pattern of feet. The second, ametrical system describes a freer
compositional approach similar to what Guido d'Arezzo would later term 'quasi prosaic song'.
Cursus mixtus
Contemporary Latin prose and poetry contained another two-fold division of approaches to
'numerus' (lit. 'number', the use of poetic formulae called clausulae at the end of lines). The
classical approach to clausulae involved ending poetic lines with set numbers of syllables
which used fixed patterns of short and long syllables, sometimes involving syllabic stress, and
rhyme.
By the third century, a new fashion developed and rose into prominent use by both Christian
and pagan during the time of St Ambrose and St Augustine. This new approach to clausulae
could still end poetic lines using set numbers of syllables, and often involved rhyme, but it
disregarded long and short syllables and instead focussed on patterns of syllabic stress. Both
approaches were in use from the third to sixth centuries AD and this two-fold 'numerus' is now
called 'cursus mixtus' (mixed course/way). The old classical technique died out after this
period.
When we have a continuous succession of
definite feet, which is spoiled if unsuitable
feet are introduced, it is rightly called
rhythm, i. e. number; but because this
succession has no limit and no particular
foot has been selected to mark an ending,
this absence of [poetic] measure in the
series does not allow us to call it [formal
poetic] metre. For [formal poetic] metre
involves two things: it proceeds by definite
feet, and it has a definite limit. And so it is
not only [formal poetic] metre because of its
fixed limit, it is also rhythm on account of
the orderly combination of its [formal poetic]
feet. Thus all [formal poetic] metre is
rhythm, but not all rhythm is [formal poetic]
metre. In music, the word rhythm is so wide
in its scope that everything therein which
concerns the longs and the shorts is called
rhythm.
Whatever is not limited by a fixed ending
but yet proceeds in orderly fashion with
properly organized [musical] feet we call
rhythm.
Nam quoniam illud pedibus certis
provolvitur, peccaturque in eo si pedes
dissoni misceantur, recte appelatus est
rhythmus, id est numeris: sed quia ipsa
provolutio non habet modum, nec
statutum est in quoto pede finis aliquis
emineat; propter nullam mensuram
continuationis non debuit metrum vocari.
Hoc autem utrumque habet: nam et
certis pedibus currit, et certo terminatur
modo. Itaque non solum metrum propter
insignem finem, sed etiam rhythmus est,
propter pedum rationabilem
connexionem. Quocirca omne metrum
rhythmus, non omnis rhythmus etiam
metrum est.Rhythmi enim nomen in
musica usque adeo late patet, ut haec
tota pars ejus quae ad diu et non diu
pertinet, rhythmus nominata sit.
Quod autem non esset certo fine
moderatum, sed tamen rationabiliter
ordinatis pedibus curreret, rhythmi
nomine notavit.