Headed by the great Curtis Mayfield, The Impressions provided a critical link between '50s R&B and '60s soul. In fact, they pioneered and symbolize the sound of "Chicago soul," a marriage of gospel, rhythm & blues and pop influences with a timely social conscience, as opposed to what was coming out of Berry Gordy's shop in Detroit at the time. Mayfield's affinity for lyrics and melodies melded brilliantly with the vocal harmonies of Sam Gooden and Fred Cash (The Impressions' classic line-up, because original lead singer Jerry Butler began his solo career in 1959, and the brothers Arthur and Richard Brooks left the group in 1962). Their sound brought Mayfield and his distinctive falsetto to the spotlight, and inspired a wealth of harmony groups around the world. The Impressions' style was marked by airy, feather-light harmonies and Mayfield's influentially sparse guitar work, plus, at times, understated Latin rhythms. If their sound was sweet, elegant and lilting, it remained richly soulful thanks to the group's firm grounding in the gospel tradition. They popularized the three-part vocal trade-offs common in gospel but rare in R&B at the time, and recorded their fair share of songs with spiritual themes, both subtle and overt.