This lovely piece comes from Langlais' 24 pieces for harmonium or organ.
The piece is registered for Salicional and Bourdon, with addition of Gamba every so often and later a Voix Celeste. I've stuck to the intentions of the registration as closely as the Klais will allow.
By the way, there is a part near the end where I slipped changing manuals and you hear a 'cough' of a flute for a split second. I tried to edit it out but made it sound worse than just leaving the mistake in!