I don't know whether it is the first time, but Leibniz discussed the
harmonic triangle in "Historia and Origo Calculi Differentialis"
(1714), published in 1849.
>In Annapolis, several years ago, one could find bumper stickers on cars
> Honk if you love Leibniz.
>Is the word *honk* known to our non-native-English speakers?
"Honk", "honkie" and "honky-tonk" are taught in english courses for
french people. I'm not sure that Leibniz would like this tribute...
Best wishes from Versailles