This music is transcendent.
My niece posted this on Facebook.
I quote her here because it's an interesting story:
This piece was apparently so mind-bendingly beautiful the Vatican "guarded" it for years, not allowing anyone to listen to it outside of the Sistine Chapel. It wasn't available to the masses until Mozart "stole" it, transcribing it from memory for the populace to hear.
https://www.youtube.com/watch?v=jZL3PO