Abstract Everything—as the saying goes—is relative. If so, then Symphony No. I is a typical work, for many of Haydn’s symphonies from the late 1750s and early 1760s have similar overall plans and similar treatments of the forms of the individual movements. By the same standards, Symphony No. 21 is an extremely unusual symphony. As such, it is a particularly useful subject for analysis, offering us a valuable opportunity to test our understanding of Haydn’s formal procedures against a number of problematic movements.