“Let’s Cool One” is a tune written by Thelonious Monk. This composition is one of Monk’s more traditional pieces in the sense of jazz harmony. Some of Monk’s pieces tend to swerve in and out of keys and take some unexpected turns, but Let’s Cool One stays fairly centered on Eb major. Monk was an incredible writer of melodies and this one is yet another great example. Check out the recording! You can find it on Monk’s “Misterioso” record.