During his career, Carl Ruggles was considered to be at the forefront of American contemporary music. His techniques of non-repetition of tones in melodic lines and the saturation of the vertical and horizontal domains with half-steps created a version of atonality which shares a philosophical basis with Schoenberg, but differs sharply in practice. Within a progressive vocabulary, Ruggles' music shows a foundation in tradition. He made much use of traditional sixteenth century guidelines for the construction and interconnection of individual lines, and his method of motivic development and variation are based in the music of the nineteenth century. Like Schoenberg, he applied the fundamental concepts of the past to his own atonal vocabulary and musical ideal.