Billy Strayhorn started writing for Duke Ellington in 1939 at the age of twenty-four. From then until his death, he was Ellington's most consistent collaborator. Though Ellington used to say that he and Strayhorn had almost identical musical thoughts, that's not quite true. Strayhorn's musical ideas were more formal and impressionistic. Ellington's were more palpable and blues oriented. Over they years, they influenced one another. Strayhorn wrote many songs by himself, the most well known are "Take the 'A' Train," "Lush Life" and "Chelsea Bridge."