Petrus de Cruce

Petrus de Cruce, also known as Pierre de la Croix, was a late thirteenth century composer and author.  He wrote a treatise on mensural polyphony, which did not survive.  However, several of his motets are extant, and they provide interesting insight into his notational theories.  In his motets the triplum was much faster than that of any of his contemporaries, while the tenor and duplum voices held long notes.  It is possible these could have been for solo voice with accompanying instruments.

The significance of Petrus de Cruce is his implementation of a greater selection of rhythmic choices.  Before the end of the thirteenth century, all composers were limited to either perfect prolation or imperfect prolation.  Prolation is the division of the breve into semibreves.

He expanded upon the subdivision of the breve.  Until his point each breve could be divided into two seibreves or three semibreves.  Petrus de Cruce declared that any number of semibreves, up to seven, could occupy the space of one breve.  He states that any two groups of semibreves must be separated by a punctus, which was a new concept.  His notational innovations were an important precursor to the development of the Ars Nova style.