“I had hoped I wouldn’t fall in love with another orchestra, but in fact I did,” sighs Sir Simon Rattle. And who is the mysterious new love? The Freiburger Barockorchester. Their Schumann evening in Lucerne reveals exactly what this newfound happiness sounds like. The orchestra plays with clarity and lightness, in shimmering colors yet firmly grounded. The program opens with the highly romantic overture to Schumann’s only opera, Genoveva. Isabelle Faust — whose violin sound is so human and communicative, and whose phrasing is unmatched in its delicacy — then performs the Violin Concerto. Schumann wrote it shortly before his mental collapse, and it did not receive its world premiere until 81 years after his death. “It’s music that moves you deeply,” Faust says. The same is certainly true of the Second Symphony, which many consider Schumann’s finest. Its unearthly beautiful slow movement has something of a prayer of thanksgiving about it: Schumann continually unfolds an enthralling melody, letting it rise and expand until it seems to glow — ten minutes of eternity.