Finnish composer Jean Sibelius once wrote, "Compositions are like butterflies. Touch them even once, and the dust of color is gone. They can still fly, but are nowhere near as beautiful." That is, let your ears and your gut be your guide, not your analytical mind. We'll admire a musical butterfly this hour: the Symphony No. 7, by Sibelius. Also on the way, a world-premiere performance of chamber music inspired by ephemeral sculptures of Andrew Goldsworthy. On Friday's Performance Today, from APM.