I missed a big chunk of yesterday's Simpsons because it was delayed by some silly game and the DVR is not smart enough to compensate.
But in what I saw, the Aquarium by Camille Saint-Saëns (from Le Carnaval des Animaux) played a significant role. It was the soundtrack during the home movie. (I wish I could say I identified the piece on my own, but the closed-captions gave it away. In fact, they're often helpful for decoding cultural references in the Simpsons, e.g.: [March theme from The Great Escape (1963) playing.])
It occurred to me that I don't have much Saint-Saëns in my collection. Now, I'm not typically an enormous fan of French impressionists – in music or painting – and I guess I sometimes lump Camille in with Debussy and Ravel. Maybe not an entirely accurate classification, but I'm not a musicologist. Anyway, I certainly enjoy the Saint-Saëns Organ Concerto. In fact, I thought I had a copy, but if so, it never made its way onto my hard disks. (My grandmother was a big fan of that piece, having encountered it in the France part of Epcot… I believe it's the soundtrack during the simulated lift up La Tour Eiffel. Took us several visits to identify it when I was a kid.)
No, it turns out the only Saint-Saëns in my collection is The Swan from Carnaval – probably the most famous piece therein, and part of some other compilation – and a Havanaise for violin and orchestra. Will have to remedy that.