The sky had the hard, black quality of polished onyx studded with brilliants – the constellations. Orion, who rules the winter night, shone clear, a celestial guardian on the walk home. Looking up and catching sight of the tight line of three stars which comprise his belt recalled the three, falling silvery notes sounded by the piccolo to open Kaija Saariaho’s Ciel d’ hiver, a 2013 orchestration for smaller forces of the second movement of her 2002 piece, Orion. I realized I was walking under her sky, the one I had heard unfold that afternoon in Symphony Hall.

Like her compatriot Sibelius, whose last two symphonies closed the program, Saariaho is above all a colorist, creating out of natural phenomena a musical cosmos with its own peculiar laws of time and space. The harp and celesta quietly chime like a clock striking the hour, just before the piccolo introduces the three notes which will drift from section to section throughout, gradually evolving and shifting color, rhythm and tempo. An ostinato of low strings paints the dark expanse of night. A rich variety of percussion chimes in with a glitter of crystalline flurries. Clouds briefly darken the scene as the three-note theme grows in density to form a series of chords in the lower ranges of the orchestra. The ticking clock returns to count down to the closing combination of a fading sliver of high violins, strokes to the glass chimes and the faint rustle of the shell chimes, as everything fades back into silence. John Storgårds, who overlapped Saariaho at the Sibelius Academy in Helsinki, transformed afternoon into evening with an expansive and translucent account which captured the contrasts of color and texture in painterly fashion. Time was stretched so thin it ceased to exist, and for the brief duration of the piece we were one with the universe. Saariaho was in attendance for the entire program and came out to warm, appreciative applause.

Mozart’s Piano Concerto no. 22 in E flat brought everyone back to earth with a lively party of interesting characters and puckish humor. Like the best actors, pianist Martin Helmchen not only acts but listens and reacts. Each movement had a vivid character and purpose of its own, reflected not only in his touch and pedaling, but in his demeanor and his conversation with the Boston Symphony Orchestra. Where others opt for composure and elegance above all, he brought out the drama, whether serious or comic. The Allegro was bold and extroverted, played with assertive touch, plummy tone and a hint of playful bluster as the piano’s gentle mocking undermined the martial overtones of the orchestra’s introduction. A lighter touch and limpid timbre colored the long unbroken lines of his plangent and introspective Andante. The rollicking hunting theme of the final movement sparkled, with Helmchen transforming some of the rapid fingering at the higher end of the keyboard into peals of laughter. The slower section danced with modest grace before the hunters’ final romp. Storgårds used a moderate-sized orchestra, which he had playing with the lightness and transparency of a smaller ensemble, in a lively give-and-take with his soloist. Helmchen's intriguing cadenza was composed by his brother-in-law, Martin Hecker.

Nature may have spoken to poets like Wordsworth, but it sang to Jean Sibelius. At his lakeside home in the country, he could hear modes and overtones in mundane natural phenomena. His final two symphonies – “professions of faith” as he called them – are permeated by his lifelong, mystical bond with nature. Storgårds began the Sixth without a baton, shaping the shimmering waves of sound in the first movement with cupped hands. The baton returned for the remaining movements, but the fluvial flow remained. As a profession of faith it was both querulous, urgent, and ruminative, the abrupt endings to two of its movements looming question marks which the prayerful, liturgical feel Storgårds gave to the closing did not adequately answer.

From the initial timpani taps triggering a rising mass of dark, dense chthonic sound, the Seventh unfolded, after a brief pause, like the curtains of the Northern Lights which sweep in an unpredictable pattern across the night sky, rippling, fading, flaring, hues changing in color and intensity – an enveloping sound picture which induced a devotional rapture in the face of the score’s more agitated passages. Once again, we were briefly out of time and swaddled in the immensity of the universe. Some see the intense final chord as an existential cry on a par with Munch’s Der Schrei der Natur. This afternoon it was not only an echo of the opening, but a grand and bittersweet Amen. As he did with the Saariaho, Storgårds held the silence, postponing applause. We ended as we had begun, in cosmic quietus.