Antonio Cornazzano used the image of a
"ladder" to show the proportions or ratios
in dance steps. These "step ratios" or "misura"
are to be matched (or harmonize) with the
accompanying music, based upon
"mensuration".
("The Platonic Theory of Ethos in Fifteenth-Century
Italian Court Dance", Jennifer Nevile, Literature
and Aesthetics, vol. 3, 1993, pp. 45-47.)
It has been pointed out that Domenico da Piacenza
wanted a simple method for dancers to know how
fast they should dance for each type of misura.
His pedagogical rule was quaternaria misura is
one-sixth faster than bassadanza, saltarello
misura is two-sixths faster than bassadanza, and
piva misura is three-sixths faster than bassadanza.
This is an easy rule for dancers to remember.
However, this rule is in slight error. Quarternaria
misura is actually 3:4 ratio (0.75) but the music
requires 5:6 (0.83). It has been pointed out that
"misura" is "without strict time". (See
"Harvard Dictionary of Music", Willi Apel, Harvard
Univ. Press, 1962, p. 451).
.
It should be noted that these "misura" are
an attempt to use the Pythagorean harmonic ratios
in dance, but also in harmony with music. Art is not
science: the music and dance must be slightly modified
to produce an overall effect that is aesthetically
beautiful.