Stevie Wonder's musical genius is so potent, he even put his own joyously funky stamp on “Happy Birthday.” His reinventions don't stop there: The Paul McCartney duet “Ebony and Ivory” elegantly deflates racist hangups with a keyboard metaphor; his anthemic “As” transforms love into a world-conquering force. Wonder's prodigious playing and devotion to soulful innovation power one of the rock era's most gem-studded catalogs.