This is a choral/orchestral arrangement of the Toccatta from Organ Symphony #5, by Charles-Marie Widor (1844-1947). In its original form, it's *much* faster. Often used for recessional music at weddings!
However, I don't know if Mr. Widor is responsible for the choral/orchestral arrangement.
"You are only young once, but you can stay immature indefinitely." - Ogden Nash