Gallus Dressler (16 October 1533 – 1580/9) was a German composer and music theorist who served as Kantor in the church school at Magdeburg. Though a few of his works have remained in the choral repertoire, he is best known for his theoretical writings, especially his Praecepta musicae poeticae (MS, 1563), which contains some of the earliest detailed description of the compositional process of the Renaissance motet. Source : Wikipedia