This feature was of important rhythmic concern to Guido and 11th century commentators.
On account of the tenor, Guido says it is necessary to beat a chant like metrical feet.
Like Hucbald and the anonymous writer of De musica before him, Guido understood lines of
chant as having three building blocks or units. He also described the smallest musical unit
(his musical syllable) as a 'neume' (gesture) but also used the word neume to designate a
musical unit of two musical syllables.
The tenor (hold) is a feature connected with the ends of the syllables and parts and
distinctions. This appears to have been an extension of the last note, a way of holding the
last pitch to mark the end of a neume, phrase or line of melody. It was seemingly shortest in
length for a neume, larger for a phrase and longest for a line.
Guido of Arezzo, Micrologus (1026-28), Caput XV.
Brussels, Bibliothèque Royale, II 784, ff.12r-13r,14r.
The Latin word 'morula' (a little delay) had a more flexible application than the word 'mora'
(delay) and might be best translated as 'duration'. It was used not solely in relation to
musical notes but also to whole phrases or lines. The German commentator, Aribo, writing in
the same century, saw Guido as saying here that the rhythm of a chant melody was built out
of three aspects or categories which the latter saw as 'proportionalis' (proportional) in
nature. These were i) the length or brevity of the morula, ii) the numerical combinations of
notes and iii) the ratio of the length of the tenor to the length of musical phrase.
Therefore, in the same way as in poetry
there are letters, syllables, parts, feet and
lines, so in music there are phthongi, that
is, notes, of which one, two or three are
fastened into syllables and the same alone
or doubled [into] a neuma, that is, they
establish a part of a little song, and one
part or several make a distinction, that is,
a place suitable for breathing. Regarding
which, that must be noted so that each part
is succinctly notated and expressed, a
syllable even more succinct.
A hold, that is, the mora of the last note -
which however small it is in a syllable is
larger in a part and longest in a distinction
- is a sign of division in these, and so it is
necessary that a little song should be
clapped as if with metrical feet and that
some notes should have a duration twice
as long or twice as short compared with
others, or a shake, that is, a varying hold,
which is sometimes shown to be long by a
plain virgula added to a letter.
And above all, such care should be taken in
the distribution of neumes so that, since
neumes are made either by repercussion
of the same note or by linking of two or
more, neumes are related to each other,
always however either in the number of
notes or in ratios of holds, and answer
now equal to equal then double or triple to
simple or else three to two, or four to three.
Let the musician lay out for himself from
which out of these divisions he may make
the kindled song, like a poet [lays out] from
which feet he makes a line of verse.
except that a musician does not constrict
himself by such a compulsion of rule,
because, in everything, this art alters itself
throughout by rational variety in the
arrangement of sounds. ...
Like as in the way of running of a horse, at
the ends of distinctions, notes should
always come to a place of breathing more
Igitur quemadmodum in metris sunt
litterae. sillabae. partes. pedes. ac
uersus. ita in armonia sunt ptongi. id
est soni. quorum unus duo uel tres
aptantur in sillabas. ipsaeque solae uel
duplicatae neumam id est partem
constituunt cantilenae. et pars una uel
plures distinctionem faciunt. id est
congruum respirationis locum. De quibus
illud est notandum quod tota pars
compresse et notanda et exprimenda
est. sillaba uero compressius.
Tenor uero id est ultimae uocis mora.
qui in sillaba quantuluscumque est.
amplior in parte. diutissimus uero in
distinctione. signum in his diuisionis
existit. Sicque opus est. ut quasi metricis
pedibus cantilena plaudatur. et aliae
uoces ab aliis morulam duplo
longiorem uel duplo breuiorem. aut
tremulam habeant. id est uarium
tenorem. quem longum aliquotiens
apposita litterae uirgula plana significat.
Ac summopere caveatur talis
neumarum distributio, ut cum neumae
tum eiusdem soni repercussione. tum
duorum aut plurium conexione fiant.
semper tamen aut in numero uocum.
aut in ratione tenorum neumae
alterutrum conferantur. atque
respondeant. nunc equae equis. tunc
duplae. uel triplae simplicibus atque alias
collatione sesqualtera. uel sesquitertia.
Proponatque sibi musicus quibus ex his
diuisionibus incedentem faciat cantum.
sicut metricus quibus pedibus faciat
uersum. nisi quod musicus non se tanta
legis necessitate constringat. quia in
omnibus se haec ars in uocum
dispositione rationabili uarietate
Item ut in modum currentis equi semper
in fines distinctionum rarius uoces ad
locum respirationis accedant.