Guillaume Costeley

Nothing is known of him prior to his arrival in Paris in or before 1554, at which time he met, and became acquainted with the music of, such diverse figures as Jean Maillard, Jacques Arcadelt, and Sandrin.

It was through Sandrin, who had recently worked in Italy, that Costeley probably became interested in the latest trends in Italian scholarship, particularly the theories of Nicola Vicentino, some of which involved composition using microtones.

Costeley's only microtonal composition, Seigneur Dieu ta pitié, was apparently written at exactly the time that Sandrin was in Paris.

Since Le Roy was closely connected to the royal court through the family of Catherine de Clermont, who was to become the Countess of Retz, it is probable that his influence was significant in Costeley's rise.

He was lauded by the group and took part in its activities (the king himself was probably a member, and attended some of their meetings, as did his successor Charles IX after 1574).

[1] A peculiarity of Costeley's style – and his notation – is that he specified the accidentals he wanted applied to his music with great care and precision, something which was unusual prior to the middle of the 16th century, but which began to occur thereafter.

It is a short fantasie for organ (Fantasie [pour] orgue ou espinette faicte par monsieur Coteley [musicien] de la Chappelle du Roy), and is considered significant because it is one of the only surviving bits of keyboard music from late 16th-century France, other than pieces transcribed from vocal originals.