Mozart D minor Piano Concerto is one of only two among 27 he cast in a minor key, so its initial dramatic impact must have been immense. It opens quietly with tensely swirling, stabbing strings alone, making for maximum impact when the rest of the orchestra thunders in. The central Romance’s major-keyed serenity also contains a minor-tonality shock. Still, although the finale opens in D minor angst, major-key sunlight eventually triumphs. The shock of Beethoven’s Symphony No. 8 of 1814 was that, after the increasing lengths and rich textures of his previous symphonies, not only did it revert to a more Haydn-esque length and lightness, but even swapped back from the now-established scherzo to a menuet for its third movement. Yet other surprises were modern in their boldness, such as replacing the slow movement with a quirky Allegretto scherzando just four minutes long.