Igor Stravinsky was a constantly changing artist. He's also the most Janus-like of all musicians — always looking forward and back at once. His work, when it was new, puzzled and challenged in equal measures. And though Cocteau virtually wrote him off early in the game, Erik Satie came to his defense in a 1922 Vanity Fair article. An artist, he cautioned, must be judged by each individual piece, and not by how these fit into his work as a whole, or square with that of other composers, living or dead. And though sometimes visceral — what could be more aimed at the gut than the 1913 Le Sacre du Printemps? — his other works, like Agon (1955-57) are sometimes seen as either inscrutably aimed at the head, or downright bad. San Francisco's crackerjack and quite glam Laurel Ensemble, which launched its third home season this fall with a concert Saturday night at Old First Church, had the inspired idea of presenting short and even shorter works from almost all periods of the composer's output, with a deuce set by two other musicians. Stravinsky, like his contemporary analogue Philip Glass, is a man of the theater, and as such both seem to mask their identities in the work at hand, so much so that some see these as impersonal, or even completely emotion-free. Will the real Igor Stravinsky please stand up? While the Laurel's offering of seven pieces by Stravinsky and three other composers didn't definitively answer that question, it did go a long way to providing one. Early (or, as Glass once described them to me, "folkloric"), middle neoclassic (c. 1920-1950), and late (serial; c. 1952-1971) periods were represented, and the Laurel made a strong case for each. Suite Italienne (1933), commissioned from Stravinsky by violinist Samuel Dushkin, showed this mask-changing artist's features in bold relief. Violinist Christina Mok and guest pianist Laurie Lack made its virtuosic demands and effects— the violin's sudden, in-a-distance, lowering of volume when it defers to the piano, for example — seem easy as pie, and Mok's tone was hard-edged, or directly emotional without being overly heart-on-sleeve. Quinto Maganini's arrangement of Rondes des Princesses (1918) for flute (the fully-in-control Sarah Holzman) from Stravinsky's neoimpressionist, folkloric Firebird (1909) made its points discreetly and with grace. Its line almost seems to channel Debussy's freewheeling one in Afternoon of a Faun.