Each of my works tends to grow out of an initial impetus. The impetus is, however, already a refined element. What first comes into one's mind is usually much more vague. It could be a persistent emotion, an intersection of unlikely factors, a need to explore and exercise a certain resource (be it pitch, motion, sonority). Then I clarify and concentrate whatever is intriguing me, spurring me to compose this new work. In the case of The Angel of Death, a combination of factors caused me to think about the phenomenon of alternative futures, the possibility that a process (a life in progress, for example) can have differing outcomes depending upon circumstance. I read extensively on the Etruscans, who appear to have believed that there was an appointed duration for an individual life, even for the life span of a society. They believed that this span could only be influenced by special pleadings and subsequent divine dispensations. This, in turn, led me to consider the figure of the Angel of Death within the Christian tradition and the possibility that one might, in certain circumstances, be granted "a second chance". As the idea of alternative futures emerged, it became clear that it could mesh well with the interests of perceptual psychologists wishing to examine the responses of listeners to the experience of musical form. I realized that if I could devise a form in which the large constituent parts could be reordered, more might be revealed about the listener's experience.
I had some initial hesitation about collaborating with perceptual psychologists, even though I had known and respected the work of my prospective colleagues for years. Collaboration involves, I believe, the necessity of interaction between participants of roughly equal maturity and experience, high mutual regard, as well as a willingness to compromise (in the interest of arriving at an otherwise unobtainable result). I was predisposed to believe that some of the difficulties which concert music has been experiencing in recent decades were traceable to a common source: unrealistic views regarding what listeners can hear, what they are interested in. I was looking for confirmation that these observations might turn out to have some foundation. I was also curious about what would happen if my own assumptions were subjected to objective assessment. In the event, my scientific collaborators and I agreed that both of our concerns could be addressed usefully, and without destructive interference.
Given the idea of alternative possibilities, we agreed that the formal experience of the work should be multifaceted, and include elements in its formal plan that were typical in traditional Western forms: thematic presentation, transitions, combinations (i.e., developments). The idea that, in formal terms, the "same" musical terrain could be traversed in alternative ways prompted further complementarities. If the work were a chamber concerto, the solo piano and the chamber orchestra could both present each thematic element and its musical relationships in strictly parallel ways. In other words, the two versions of each thematic element (one for piano, the other for chamber orchestra) would be close to identical. Only the medium of transmission would change. Given a reasonable number of thematic elements and the presumption that there would be two strata in each part (discussed below as the Sectional and Domain traversals), the roles of the two media could be reversed from one version or part to the other. What the solo piano plays in the Sectional part is given to the ensemble in the Domain part, and vice versa. [Note that the concentrated nature of the impetus (alternative paths) invites the deepening of its influence: given the presence of two approaches to formal traversal (Sectional and Domain), the thought of two media (piano and orchestra), which present material in alternate assignment in two strata, followed.]
Evidently, it was of interest for the psychologists to have access to my thematic material prior to it being embedded in a fully developed musical continuity. I was accustomed to composing thematic materials prior to their disposition and transformation within the larger work because of my involvement with computers. A commitment to brief musical themes has enabled me to foresee more explicitly how the formal opportunities I am conceiving might play out. And their existence allowed the possibility of performance and recording by instrumentalists at an early stage in the overall compositional process, making them available for transformation by digital signal processing.
The phenomenon of modularity was given special emphasis. I conceived an overall formal design that allowed for the maximal separability of components from embedded function. It was a congenial challenge to design Angel in this fashion, and the psychologists then had the opportunity to evaluate the perceptual characteristics of the thematic elements before I had actually begun to elaborate them into a finished composition. As a result of the stratification of the forms, there was also an opportunity to record and, thus to evaluate, many of the elements of the structure in the absence of the others. (Recordings of the ensemble alone and of the piano soloist were made and became the basis of psychological testing reported upon elsewhere in this CD-ROM, as well as of the computer-processed sounds.)