"Birth of the Cool' became a collector's item, I think, out of a reaction to Bird and Dizzy's music. Bird and Diz played this hip, real fast thing, and if you weren't a fast listener, you couldn't catch the humor or the feeling in their music. Their musical sound wasn't sweet, and it didn't have harmonic lines that you could easily hum out on the street with your girlfriend trying to get over with a kiss."