Polish-German conductor Marek Janowski, whose lovely Hänsel und Gretel the week before marked his return to the BSO after six years, ended the BSO’s fall season with an odd Laurel & Hardy pairing: Bartók’s haunting and delicate Third Piano Concerto, a loving bequest to his wife and frequent piano partner, Ditta Pasztory (he had completed all but the last 17 bars when he died, in 1945), and Richard Strauss’s last major tone poem, the inflated Alpensinfonie ("Alpine Symphony"), from 1915, a work that takes nearly an hour and more than 100 players to get through. That Janowski made sense of both pieces is a testament to his musical sensibility.

This Bartók concerto is not the one the BSO had scheduled. Hungarian pianist Zoltán Kocsis was set to perform the drivingly rhythmic, sometimes abrasively dissonant Second, but he cancelled, and his replacement, 33-year-old Polish-Hungarian virtuoso Piotr Anderszewski, in his BSO debut, preferred the Third.

The concerto begins in quietude — a nostalgic Hungarian melody in the piano surrounded by murmuring strings. Then piano and orchestra trade places — the orchestra takes over the melody while the piano shimmers with high-lying trills. Big-handed, fresh-faced, and gangly, Anderszewski has an appealing openness, a darkly burnished tone, and effortless accuracy. He played the theme with eloquent understatement, as if he were refusing to wallow in the beauty of this moment, holding back almost stoically.

Janowski, too, refused to force. The slow movement, Adagio religioso, seemed to float in a spiritual trance, piano and orchestra alternating again, the steady series of piano chords growing darker and increasingly intense, the orchestra responding with a solemn chorale. But there are also the enchanting twitterings of birds — fluttering piano, chirping winds, and pizzicato strings. Bartók ends happily, with a playfully contrapuntal Allegro vivace and only occasional hints of shadows.

The Strauss began with a shaky entrance in the low brasses, and there was some raucous brass playing throughout (a lot of brass to polish in this piece, including 12 off-stage players). But it was evident that Janowski was closely following Strauss’s plot: a mountain climb, the summit achieved, the quick descent in a sudden storm. The Alpine Symphony is explicitly illustrative — a soundtrack without a movie. We see a waterfall cascading. We "hear" a sunrise. We pass a pasture and listen to the cowbells (Strauss may be recalling Mahler’s Sixth Symphony — perhaps this is his elegy for Mahler, who died in 1911). We reach the summit in a glorious climax. A storm rumbles, then explodes in thunderbolts and lightning flashes (there are both wind and thunder machines). A pious organ (James David Christie — another keyboard wizard) intones before the "Dying Away of Sound" ("Ausklang") and the return of "Night."

Janowski never pumped the climaxes — he seemed simply to be riding their waves of rising and falling. There wasn’t a moment of macho self-congratulation. In the mysterious, almost visionary moment after the arrival at the summit, he allowed the soloists — first cello, then trombone, horn, trumpet, and finally a lonely oboe (expressive, articulate John Ferrillo) — real breathing space in which to establish their identity.

Too bad the Alpine Symphony isn’t a more inspired work. Almost every effect has a more vivid precedent in earlier Strauss — or Wagner. Still, we’re not likely to get a better performance in the near future. And if we’re lucky, we won’t get another one at all for a while.