The Beaux Arts Trio modulated smoothly from the sublime (Mozart) to the ridiculous (Charles Ives) last night in the Library of Congress, without showing the least sign of strain. The transition was made easier, perhaps, because the ridiculousness of the Ives Trio (which could be nicknamed the "Name That Tune Trio") is both sublime and deliberate.

The Ives reaches its climax in the second movement, which is cryptically titled "Tsiaj"--the only occurence of that inscription in all of music. A footnote informs the curious that the heading is an acronym for "This scherzo is a joke." This is logical enough, since "scherzo" is the Italian word for "joke," though some works in that form (Chopin's, for example) are only fleetingly funny. Ives' is very funny: a collage of fragmentary popular and hymn tunes piled on top of one another, twisted around and jumbled, reaching a sort of climax when the violin belts out "Ta-ra-ra-boom-de-ay." The piano, violin and cello spend much of the movement running off in totally different directions, but they manage to find and pursue common interests by the time the movement reaches its end.

Then they become quite serious in the finale, which ends with the cello singing "Rock of Ages," joined eloquently by the violin for a second chorus and by the piano for a sort of final "Amen." Last night, cellist Bernard Greenhouse played it beautifully--even reverently--on the Castelbarco cello, built by Stradivari in 1697 and given to the Library of Congress by Gertrude Clarke Whitall. The instrument sounded as though it had been built to play this tune, and throughout the evening it enhanced Greenhouse's always excellent playing--even in Mozart's Trio in B-flat, K. 502, where he didn't really have a lot to do.

The Mozart was largely a showcase for Menahem Pressler (a superb Mozart pianist) and violinist Isidore Cohen, who made the slow movement a moment of memorable beauty with exactly the right proportion of schmaltz. After such a first half, it was hard to avoid a sense of anticlimax, but the Op. 8 trio of Brahms managed the trick, particularly in the exquisite middle section of its scherzo. The program will be repeated tonight and broadcast live on WETA-FM at 8. It is worth considerable effort to hear it.