Taylor Swift is in the news, so let's celebrate "Trouble" from the album "Red." This song is so ubiquitous, it's easy to imagine that it just grew up out of the soil like a blade of grass. But in fact it's the end result of some smart calculations. Once upon a time-- A few mistakes ago-- I was in your sights-- You got me alone. Like a memoir writer, Taylor immediately establishes that this story involves twins: "Taylor Then" and "Taylor Now." Taylor Now will empathize with but also lightly mock Taylor Then: The sense of ambivalence creates tension, and it also creates humor. By opening with fairy-tale lingo, Taylor Now is making fun of her own wide-eyed reputation. And it's a nice touch to measure time in "mistakes." I guess you didn't care-- And I guess I liked that. And when I fell hard-- You took a step back-- Without me. And he's long gone When he's next to me. And I realize The blame is on me. Taylor is...