600 Lines and How Now were the first compositions written for the Philip Glass Ensemble which began to rehearse and perform regularly in 1968.
The purpose of this early ensemble music was two-fold - First, to extend and develop the music I had begun in 1965 based on repetitive and cyclic structures. Second, when broadening the performance to the ensemble of synthesizers and wind instruments, it was clear that a new performance technique would need to be developed. In fact, every new musical language requires new performance skills. When a musical language is truly new (even radical) there is no other way than to develop the appropriate method or technique of its performance.
Works such as 600 Lines were, in effect, "practice" pieces for the new ensemble to develop those skills. These included, besides stamina and sustained concentration, the ability to play continuously in a relaxed, easy and joyful manner. I am very pleased to note that the Alter Ego ensemble has accomplished all these.
600 Lines, furthermore, presented a new series of problems that have to do with the system of notation that I was then developing. In fact, the highly extended scores that the musicians had to read from led to a new crisis for me, this time regarding music notation. This new problem became the subject of new compositions and eventually led to the formulation of the "additive process," first heard in Two Pages composed the following year, and the foundation of much of the music of the ten years that followed.