Tchaikovsky never ceases to amaze me with his ability to create gorgeous melodies of varying moods and texture. They all seem to have a unifying 'Tchaikovsky-ness' that I can't quite put my finger on.
This song is from an opera that he scored called Eugene Onegin. The opera is based on a story by the Russian poet, Alexandre Pushkin (who's work also inspired another work of classical music that I really love). Pushkin's story involves a man who spurs the romantic advances of a very kind and all around wonderful woman, and of course he later regrets it, tragic Russian-ness, and so forth. I don't know how good the opera is, but this Waltz from the beginning of Act II is a masterpiece in and of itself. The main theme is very sweeping and romantic, played at a moderate tempo with lots of bounce. But there is also a lot of strife present in the music, reflecting the turbulence in the story.
Next Up: Bolero by Maurice Ravel