This album covers roughly two years in Rollins's career when he was beginning to emerge as an important force in contemporary jazz. "I Know" was his first track as a leader, taped at the end of a January 1951 Miles Davis date at Davis's insistence. (Miles even played piano for him.) Sonny's first date as a leader took place on a snowy December night at the end of that year. The meeting with the Modern Jazz Quartet, in October 1953, showed a new maturity, especially in the rendition of Ellington's "In a Sentimental Mood."