Here is another setting of Conditor alma siderum — our Sequence hymn for the season of Advent — and the earliest setting I’ll be presenting. It’s by a prominent 15th-century composer, Guillaume Dufay (1397-1474). Dufay was one of the leading composers of his time, and a widely influential figure in shaping the direction taken in the music of the Renaissance. Ordained a deacon, then a priest, Dufay became a member of the choir at the Papal chapel in Rome. But it was an era of great turmoil in the Church, with tumultuous Councils, schisms, and an antipope. Perhaps that explains why Dufay traveled a lot, which extended his aesthetic influence across Europe. In…