Changes: 64 Studies for 6 Harps (1985) is a large-scale work that combines and connects many of James Tenney's (1934 - 2006) most important theoretical and musical ideas, including gestalt segregation principles and complex intonation systems. Composed with the aid of a mainframe computer at York University, the piece also marks a return to computer-aided, algorithmic composition after a long hiatus. It was one of the first pieces Tenney composed with a computer after he left New York City in the late 1960s to teach at the California Institute of the Arts. After Changes, the majority of Tenney's works involved computer software and formal, algorithmic processes. Tenney was both a prolific composer and theorist but rarely wrote in detail about his own pieces even though his music consistently implemented his theoretical ideas. One exception is his article, "About Changes," originally published in the journal Perspectives of New Music. "About Changes" is a detailed and exhaustive theoretical companion to and description of the piece that carefully documents his compositional procedures, many of which are highly technical and/or mathematical. At the beginning of the article, Tenney writes, "My intentions in this work were both exploratory and didactic. That is, I wanted to investigate the new harmonic resources that have become available through the concept of "harmonic space" much more thoroughly than I had in any earlier work. At the same time I wanted to explore these harmonic resources within a formal context that would clearly demonstrate certain theoretical ideas and compositional methods already developed in my computer music of the early 1960s, including the use of stochastic (or constrained-random) processes applied to several holarchical perceptual levels, both monophonically and polyphonically. The references to the I Ching, or Book of Changes, in the titles of the individual studies derive from correlations that were made partly for poetic/philosophical reasons but also - and perhaps more importantly - as a means of ensuring that all possible combination of parametric states would be included in the work as a whole. I must confess that I frequently thought of the twenty-four preludes and fugues of J.S. Bach's Well-Tempered Clavier as a kind of model for what I wanted to do with the work, although it seems highly unlikely that these studies themselves will ever betray that fact to the listener."
