John Dunstable (1380-1453)
John Dunstable was an English composer of polyphonic music (a style of music which consists of two or more relatively independent musical lines that sound simultaneously). Dunstable was active as a composer from the late medieval period until the early Renaissance. He was very well known as a composer in England and across Europe.
The motet Sancta Maria by Dunstable is full of triadic harmony (chordal harmony) and sounds quite modern for its time. A lot of music back then was based on modes (early scales), and harmony as we now know it didn’t exist at that time. The main musical line in the motet is taken by the Tenor voice.