Bach's "Christ lag in Todesbanden" and Samuel Barber's "Adagio"
It occurred to me that taking just the first half-bar of Bach's "Christ lag in Todesbanden" BWV 625,

https://www.youtube.com/watch?v=fcqtSNFjtHQ (played slowly and majestically)
https://www.youtube.com/watch?v=6CEWxEzfnxc (played at twice the speed and with a lighter mood)
https://www.youtube.com/watch?v=rqwgeKOgezg (with score shown)

and slowing down so drastically that the little transient notes in the middle voices in Bach's uptake are drawn out to become the main harmony - we get the main theme of Barber's famous "Adagio", which consists of just two harmonies (IV 7, V) and a slow winding melody.

https://www.youtube.com/watch?v=FOwRW8ee4S8 (arrangement for the choir, with score shown)

The harmony IV 7 is found directly in the second half of Bach's uptake. It's Bach's trademark voice leading, where the voice "must" proceed according to a set pattern - as if driven by a mathematical calculation - even though this produces a dissonant harmony. Hundreds of years after Bach's, these harmonies are still as jarring. The dissonant harmonies are, of course, intentional in Bach; but they, at the same time, make his music harder to listen to, because he does not hide them. Maybe this is why mathematicians and scientists like Bach's music more than other non-musicians.