Original: At age 17, upon moving to Paris, he took private organ lessons with Charles Tournemire, whom he assisted at Basilique Ste-Clotilde, Paris until 1927.
Simplified: When he was 17 he went to Paris and had private organ lessons with Charles Tournemire. He became Tournemireâ s assistant at the Basilique Ste-Clotilde, Paris until 1927.