Like all double albums, Songs in the Key of Life is imperfect but audacious. If its titular concern - life - doesn't exactly allow for rigid focus, it's still a fiercely inspired collection of songs and one of the definitive soul records of the 1970s. Stevie Wonder was unable to control the springs of his creativity during that decade. Upon turning 21 in 1971, he freed himself from the Motown contract he'd been saddled with as a child performer, renegotiated the terms, and unleashed hundreds of songs to tape. Over the next five years, Wonder would amass countless recordings and...