A discussion unfolded recently on a friend’s Facebook page, stemming from a post in which that friend invited the community’s thoughts about the functional identity of the chord three bars from the end of Chopin’s well-known Prelude in E minor, op. 28 no. 4. This chord is spelled as a C major triad over a bass B♭, emerging out of a larger context of E minor (albeit a rather chromatically charged E minor), and pointing toward the composition’s final, key-affirming cadence that begins after a pause in the next bar. Over the course of the next two hours or so some twenty musicians weighed in with opinions, some thoughtful, some sarcastic; some well-thought-out, some quickly and understandably dashed-off (it’s Facebook after all); some wellversed in mid-nineteenth century harmonic idioms and some coming to it as outsiders. All of the musicians that contributed belong to an extended community, variably linked via numerous professional and personal networks, not least by their shared e-friendship with the original poster.