Revising has long been a common practice among composers. J. S. Bach made changes as a matter of course when making a new copy of a work. Chopin revised habitually, even marking changes on published versions of his compositions.
Several composers whose music I love reworked some of their compositions over periods lasting years. Berlioz, for example, based his Damnation of Faust on a work he had composed 17 years earlier. Tchaikovsky completed the final version of Romeo and Juliet 20 years after the premiere of the first. Stravinsky made revisions for various reasons, including numerous changes and additions of detail in his orchestrations. Mahler revised most of his symphonies extensively.
Such decisions to revise usually stem from a persistent pursuit of eloquence.
After I began writing librettos and operas, I increasingly approached my work with a dramatist’s frame of mind. And the more experience I gained working from a theatrical perspective, the more I wished that I had composed and orchestrated a number of my earlier works with more élan—with more vivid exteriorizing of fervor.
Eventually, if I looked back at one of my earlier scores, I sometimes found myself spontaneously revising passages in my head—mentally I was unexpectedly hearing them performed differently than the way I had originally imagined them.
These differences were often subtle—changes of texture, orchestration, rhythmic detail, and so on. But when I imagined the cumulative effect of such changes, the differences in expressive effect often felt remarkable. So in a handful cases I decided to revise the earlier score to match the music I was hearing in my more unbridled imagination. Occasionally, a few changes cascaded into an unplanned reimagining of the entire work.