“Peg” is the opening tune on the second side of the 1977 Steely Dan LP “Aja”.
Like a number of Steely Dan songs, it is actually based partially on the 12 bar blues form. However, as with other Steely Dan songs derived from the blues (other examples are “Bodhisattva”, “Chain Lightning” and “Josie”), the chordal structure and voice leading is…different.
As Fagen explains, the idea was to build the verse harmony around a major seventh, not a flat seventh. Also present are additional sections; the introduction, which is derived from the chorus, and a stop/transition, based on jazz bebop harmonies, between then first chorus and the start of the second verse.
Fagen, prompted by Warren Bernhardt, who played piano on several 1990s Steely Dan tours, walks through an explanation of how “Peg” is constructed in two parts.
It is a beautiful explanation of how the underlying harmony of what superficially passes for a 12-bar blues was developed into something altogether more interesting.
