John Lee Hooker's moody shadow looms over 20th-century blues. His electric Delta sound is characterized by trance-inducing fretwork and a deep voice that communicates lust and heartache with equal intensity. The 1948 side “Boogie Chillen” perfectly captures his minimalist grooves: at first cyclical, then wildly elastic. “Boom Boom” became a pop hit in 1962 thanks to his infectiously sensual coos and growls, coupled with his band's house-rocking punch. Hooker's sense of time was deliciously erratic, something that's evident on the 1971 cut “Sittin' Here Thinkin',” a creeping examination of jealousy.