So, I never noticed this before, but here is the overture to Mendelssohn's Melusina (very popular legend in the 19C; I wonder why?):
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And here is the overture to Das Reingold
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They are using the same intervals. But of course Mendelssohn does the usual structured thing. While Wagner... you can hear the revolutionary things he's doing with music just by listening to this overture. I will let you in on a secret. It is this overture which made me decide I must see the entire opera. One chord building over 4 minutes it was almost more excitement than I could stand. Who wouldn't want to know what happens next?