From L'organiste Liturgiste (Book 1, opus 65) by Alexandre Guilmant on the occasion of the 'Fête de la purification de la Sainte Vierge' this is the Offertoire, based on the hymn 'Lumen ad revelationem gentium'.
It's a fine piece, with interesting development in the middle section (the fugue on the Trompette of the Recit).
Sounds really at home on the Aristide sample set (not a big surprise, of course). I hope you'll like it too.