The force of Haydn’s music led him to become one of the most prolific and celebrated composers of the Classical period. His restless nature drove him to create bubbling, yearning melodies and countermelodies that scramble skyward, pause to allow a momentary fanfare, and then twirl and scamper their way back down at a frenetic pace. To suit the needs of his volcanic compositions, he had to forge new ensembles—the string quartet, the piano trio—and offer a guiding hand in the development of the symphony as a musical form, just one happy by-product of a mind in constant motion.