Martin Luther was a great enthusiast for music, and this is why it forms a large part of Lutheran services; in particular, Luther admired the composers Josquin des Prez and Ludwig Senfl and wanted singing in the church to move away from the ars perfecta and towards singing as a Gemeinschaft (community). Lutheran hymns are sometimes known as chorales. Lutheran hymnody is well known for its doctrinal, didactic, and musical richness. Most Lutheran churches are active musically with choirs, handbell choirs, children's choirs, and occasionally change ringing groups that ring bells in a bell tower. Johann Sebastian Bach, a devout Lutheran, composed music for the Lutheran church: more than half of his over 1000 compositions are or contain Lutheran hymns.