Last night's Mostly Mozart program at the Kenney Center was, in fact, entirely Mozart. Under the baton of Alexander Schneider and with the collaboration of pianist Richard Goode and clarinetist Richard Stoltzman, the Festival Orchestra reviewed the three ages of the master with his youthful and exuberant string Divertimento, K. 136, the sunny middle-period A major Piano Concerto, K. 488, and the late Clarinet Concerto. Actually, Mozart had no real late period. He died so young that the music he wrote toward the end of his life represents the full bloom of his creativity rather than any mellowing or retrospective impulse.

Scheider, who knows what makes Mozart tick, focused his attention on the inner voices and the rhythmic underpinnings and let the lyricism fend for itself, which it did splendidly.

The Divertimento had a gleeful bounce and moved precise performances of this piece, but it would be hard to imagine one with more spirit.

As he did so convincingly on Thursday, Goode again found the essence of the music as he moved through the gentle A Major Concerto with extraordinary sensitivity. He has a way of beginning a phrase in midair, with no discernible initial push, but with a sense of continuing, rather than beginning motion. In the slow movement particularly, this lent the music a sense of repose and monentum at the same time

Stoltzman was most effective in the slow movement of the Clarinet Concerto where his liquid tone and marvelous breath control projected unusual beauty. That he also has the dramatic presence to hold an audience was evident in the intense concentration accorded the slow movement cadenza.

For the pre-concert recital, Goode and Stoltzman provided a change of pace with the first of Brahms' two late clarinet sonatas. There are all sorts of hints in this piece of the impressionism that was to come, and the performance allowed these hints full scope.