According to the Internet source given below, Guillaume Gabriel Nivers was a French organist and composer. Born in Paris in 1632, figures among the most important organists of the Grand Siècle, a very pious man, he himself added Gabriel to his given name, thus mark his devotion to the mystery of the Incarnation. From 1678 to 1708, he was organist at both the Chapelle royale and Saint-Sulpice in Paris; in 1686, he was organist and singing master at the Maison Royale at Saint-Cyr. Assigned by Louis XIV the task of reforming plainsong, he also composed two books of petits motets; the first, published in 1689, was destined for convents of nuns, and the second, three years later, for the usage of the Ladies of Saint-Louis at Saint-Cyr.