Allen Toussaint helped lay the foundation for modern pop music with his songwriting, spilling his sounds into the work of a wide range of artists. His soulfulness lives on in the romantic lyrics he wrote for Aaron Neville (“Tell It Like It Is”), in Prince's deft piano work and wryly self-aware melancholy (“How Come You Don't Call Me Anymore”) and in Norah Jones' mix of vivid metaphors and jazzy blues (“Turn Me On”).