“At least one day out of the year, all musicians should just put their instruments down and give thanks to Duke Ellington,” jazz legend Miles Davis once famously said. Well, seeing as today is the 120th anniversary of the Duke’s birthday, we’re all too happy to do just that. Edward Kennedy “Duke” Ellington was born on this day (April 29) in Washington, D.C., in 1899. He would have been 120 years old. Celebrate with this classic recording of Duke’s “Mood Indigo” from 1930. The song is famous for its unique harmonization, in which a trio of instruments — trumpet, trombone and clarinet — perform the melody with an inverted structure: clarinet playing at the lowest end of its range and trombone playing at the highest. Jazz scholars have noted that this unique voicing produced a”phantom” harmonic presence, making it sound as if there was a fourth player at the mic. Listen and see for yourself. And Happy Birthday, Duke!