This work was awarded the Olivetti Prize 1959 in Rome. This was an international competition, and among the jurors were Goffredo Petrassi and Luigi Dallapiccola.
Prolation governed the relative proportion of minim and semibreve in the medieval rhythmic modal system. In the present work prolation is extended to govern greater and smaller proportions - from periods covering hundreds of bars, to the smallest 'irrational' groups - also self-evidently to super and juxta-positions of a more complex nature than simple duple and triple metres. It follows that all metronome indications are to be particularly faithfully observed.