Béla Bartók saw no reason to hide his feelings when he wrote mesto (sad) over the preludes to each of the first three movements of his String Quartet no. 6. It was 1939, after all, and he was already making plans to leave his home in Hungary for America as the threat of the Third Reich intensified. Each of these slow preludes is separated by a pregnant pause from the fast music that follows, as if Bartók were repeatedly succumbing to, and shaking off, brooding reveries over what was being lost. Or perhaps the mesto passages represent reality and the fast sections are increasingly desperate attempts at mental escape. The slow music takes over completely in the fourth movement, the quartet's finale and, as it happens, Bartók's farewell to Europe—this was the last music he wrote before his final straitened years of exile in America. The Emerson String Quartet plays the Sixth next week in their annual visit. The habitual—and unequaled—clarity, thoughtfulness, and expressiveness of their playing are ideal for untangling Bartók's knotty and emotionally wrenching music. Also, splendid UW faculty pianist Craig Sheppard will join them for Brahms' Piano Quintet, a work which so far has bored me to the point of anger. If these five can't make it work, I'm giving up on it. Meany Hall, UW campus, 543-4880, uwworldseries.org. $20–$36. 8 p.m. Tues., March 8.