Topic for a Ph.D. candidate in the history of classical music: the emergence of high-altitude summer concertizing. On the American side of the pond, the textbook case is the Aspen Music Festival, founded in 1949. But well into the 1960s, the notion of serious mental concentration after a days’ Alpine hiking and mountaineering struck the European culturati as the pinnacle of the absurd. Except in the opera-heavy pilgrimage centers of Bayreuth (for Wagner) and Salzburg (mainly for Mozart and Richard Strauss), devotees of classical music gave themselves a breather—and so did performers. But over the decades, the Aspen model has caught on in a big way. Where the peaks of Switzerland once were alive with the sounds of silence (or perhaps alphorns), there is now polyphony. Klosters Music, now in its fourth season, has a ways to go before it catches up with Verbier, today a music campus to rival Lincoln Center at full throttle. But its lineup of chamber ensembles and soloists delivers a week’s worth of quality indulgences. Headliners this year include the conductor Pablo Heras-Casado, the Hagen Quartet in tandem with the pianist Kirill Gerstein, the orchestra of the Mozarteum in Salzburg, and Sir András Schiff, aristocrat of the keyboard. —Matthew Gurewitsch