If seriousness of purpose and artistic self-effacement were the sum of musical perfection, Ernst Levy would rank among our greatest pianists.

His opening performance of Beethoven's Appassionata Sonata exemplified both virtues and flaws that were to characterize the entire concert. Levy's outstanding asset is a complete immersion in the music. He avoids flashy displays of virtuosity, and through his personal absorption has attained the unique sense of structural exposition required for a meaningful performance. The result last Sunday was a Appassionate delincated by perfectly clear phrasing, logical climaxes, and minute attention to details of rhythm. In addition, it had dramatic sweep and power that could only have arisen, ultimately, from intimate knowledge of the formal elements.

But in certain technical aspects the performance was disappointing. In contrast to his silken pianissimos, Levy's loud passages often sounded hard, sometimes even to the point of banging. His concern for detail, moreover, occasionally got out of hand; in the sonata's Andante, principal melodic ideas succumbed to the uninteresting bass line.

These failings did not badly mar the Appassionata or the closing Beethoven Sonata Op. 111, but they seriously detracted from Brahm's Variations and Fugue on a Theme by Handel. This work is rarely performed, partly because of its extreme difficulty and partly because it represents a far more abstract approach than the familiar Variations on a Theme by Paganini. Levy's playing lacked the rhythmic urgency needed to keep the Handel set form foundering, in its own intellectual richness. And a lack of clarity first apparent in the swirling Appassionata finale let Brahms' Fugue become a hodge-podge.

Had is whole approach not been so modest, it would have seemed almost arrogant to wedge five short pieces by Levy himself between Brahms' gigantic variations and the sublime introspection of late Beethoven. His Piano Pieces Nos. 6, 8, 9, 12, and 18 seemed eclectic in origin, with traces of Milhand, Bartok, and especially John Alden Carpenter. They were clearly organized but almost invariably dull. Yet they did illustrate the same painstaking care that Ernst Levy has lavished on all aspects of his musical art. ROBERT M. SIMON