After around 1320, his essay Ars Nova became the rallying cry for all "modern" composers. Philippe de Vitry was born in Paris, the son of a royal notary. Philippe served numerous French monarchs, going on political missions that led him to southern France and to Avignon to meet with the Pope. He died in Paris at the age of 70. Ars Nova means "new art" or "new method". In it, he proposed that music should use a scale instead of notes as its basis, like mathematics or language. He also advocated using instruments that were common at the time, such as the harp, vihuela (a kind of guitar), and bagpipes. Philip de Vitry was one of the first composers to put together pieces that used existing modes (families of musical notes) by writing melodies in different ways. For example, he could have a melody played repeatedly, with only a few changes each time, thus using a lot of the same notes in a small space. This is why musicians today call this type of music monophonic - it has just one voice singing throughout. Or he could have several voices singing simultaneously, with each one singing a part of the melody, thus using many notes in a small space. This is why musicians today call this type of music polyphonic - it has many voices singing together.