I recently heard two music pieces for the first time -- despite their being well-known -- and was very moved by them. The first is Vivaldi's variations on La Folia. When I heard this piece on the radio, I was stunned by the overwhelming sense of life pouring out from the music. Yes, Vivaldi always overuses the same chord progression, but I love that chord progression so kudos to him. And at any rate, these are, again, variations on an already-existing tune. It's the 12th sonata in his opus 1, Twelve Trio Sonatas for two violins and basso continuo.
The second piece is The Lark Ascending by Ralph Vaughn Williams. I took two years of music history, and I don't think Vaughn Williams was ever mentioned (nor was Tchaikovsky for that matter). I suspect this is because when you deal with 20th century music, the focus is on atonal, or at least not classically tonal, music. I remember we spent some time in class going over the ten most important 20th century composers, and had to write a 10-page essay on who we thought was number 11 (I wrote mine on Béla Bartók) (Update, 01/04/17: No I didn't. Bartok would undoubtedly have been one of the top ten. I don't remember who I wrote my paper on, but I'm thinking it might have been Olivier Messiaen). And while I've heard the name Vaughn Williams before, I can't recall ever listening to his music, which is incredible considering how important a composer he is. At any rate, this particular piece is not classically tonal but is very pentatonic, making it Asian sounding -- my kids said it sounds like Kung Fu Panda. After hearing this piece we all started listening to Vaughn Williams' music, and both my kids love it.