Composing music may be the loneliest of artistic pursuits. It is a laborious traversal of an imaginary landscape. Emerging from the process is an art work in code, which other musicians must be persuaded to unravel. Nameless terrors creep into the limbo between composition and performance, during which a score sits mutely on the desk. Hans Pfitzner dramatized that moment of panic and doubt in “Palestrina,” his 1917 “musical legend” about the life of the Italian Renaissance master. The character of Palestrina speaks for colleagues across the centuries when he stops his work to cry, “What is the point of all this? Ach, what is it for?”