Miles and Trane make rainy days better.
"So What" is the first track on the 1959 Miles Davis and John Coltrane album Kind of Blue and is often credited as one of his best works.
It is one of the most well-known examples of modal jazz, set in the Dorian mode and consisting of 16 bars of D minor7, followed by eight bars of Eb minor7 and another eight of D minor7. This AABA structure puts it in the format of popular song structure.
The piano and bass introduction for the piece was written by Gil Evans for Bill Evans and Paul Chambers on Kind of Blue. An orchestrated version by Gil Evans of this introduction is later to be found on a television broadcast given by Miles' Quintet (minus Cannonball Adderley who was ill that day) and the Gil Evans Orchestra; the orchestra gave the introduction after which the quintet produced a rendition of the rest of "So What".
The distinctive voicing employed by Bill Evans for the chords that interject the head, from the bottom up three perfect fourths followed by a major third, has been given the name "So What chord" by such theorists as Mark Levine.
While the track is taken at a very moderate tempo on Kind Of Blue, it is played at an extremely fast tempo on later live recordings by the Quintet, such as Four and More.
The same chord structure was later used by John Coltrane for his standard "Impressions".
YouTube - So What - John Coltrane and Miles Davis
(Thanks to PK for the reminder.)