His greatest success came in the 1965-66 season with MAN OF LA MANCHA (with a score by Mitch Leigh) winning the Drama Critics Circle Award as well as five Tonys. In 1967 came ILLYA DARLING based on the popular Jules Dassin film NEVER ON A SUNDAY (with a score by the movie's soundtrack composer Manos Hadjidakis) bringing the Greek film star Melina Mercouri to Broadway. His point of view about the responsibility of the lyric writer offered the following advice: "Write a lyric with beautiful words but with open vowels in the wrong places, and you won't live to hear the applause, because if the composer doesn't kill you, the singer will." And he echoed the Hammerstein dictum of what show music was all about: "Today the music must be woven into the warp and woof of the play to add a dimension, to put up another wall for the weight of the play to rest upon."