As the title of this collection plainly states, there are two Frederic Rzewskis on display here: first, the formidable virtuoso pianist who bravely rushes in where others fear to tread (most recently into Cornelius Cardew's We Sing for the Future on New Albion); and second, a prolific composer who still flies for the most part under the radar of the new-music establishment. Clearly, he does not fit comfortably in either category. As a performer, Rzewski strongly disregards the common myth that the evolution of the piano repertory ended with Bartók. As a composer, even his most radical moments - and his music runs the gamut of contemporary sonorities and techniques - remain fundamentally connected to the instrument. In our time, the hyphen between the composer-performer has opened into a chasm, but for Rzewski the difference between tradition and innovation is a fine line that he has desperately tried to erase.

That sense of connection has won Rzewski a good measure of support among other pianists who similarly keep an ear to the ground. In particular, his 36 Variations on 'The People United Will Never Be Defeated' (1975), a Chilean labour tune deconstructed into the Diabelli Variations of our time, has found a wealth of interpretational differences in recordings by Ursula Oppens (Vanguard), Stephen Drury (New Albion), both USA only, and Marc-André Hamelin (Hyperion). Even a quick comparison reveals how much room Rzewski leaves a performer to find a personal balance between strict technical proficiency, emotional connection and improvisational flourish. Rzewski's account may not have the sheer brilliance of Hamelin's virtuosity, the breadth of Drury's stylistic kaleidoscope, or the focus of Oppens' unbridled passion, but under his fingers the music exists totally in the moment, and for the duration of his performance you remain blissfully unaware that any other conception of the piece is possible.

The other works included here, all newly recorded for this release, reveal just how much People United is not a summary statement as much as an entrance into Rzewski's world. Four North American Ballads (1979), written for and recorded by Paul Jacobs earlier for Nonesuch, give similarly political work and protest songs the 'Bach chorale' treatment, adjusting for differences in time and place. The Housewife's Lament (1980), originally written for harpsichordist Judith Norell, and Mayn Yingele (1988-89), written for Oppens, are both sets of variations that manage to reflect their intended performers as much as Rzewski's treatment of the source material, with scores indicating that the improvised sections should be as long as the written music.

This makes the Bach comparison particularly apt. As one of the founders of the mid-'60s anti-establishment improv collective Musica Elettronica Viva, Rzewski found himself thrown together with the likes of keyboardist Richard Teitelbaum and jazz-based improvisers Anthony Braxton and Steve Lacy - an association that still makes him suspect in some compositional circles. Improvisation and composition still run closely throughout these works, and at times the music does feel like little more than transcriptions of a particularly inspired session. Rzewski's Fantasia, in particular, seems to exist for no other reason.

But for the most part, the music holds together on the merits of its structure as much as its performance, even when that structure incorporates extra-musical elements. De Profundis (1991), a setting for 'speaking pianist' of Oscar Wilde's letters from Reading Gaol, was written for pianist Anthony de Mare in memory of Luke Theodore, an actor with the Living Theatre. While de Mare's recording (on OOdiscs, USA only) treats both text and music as a brilliant modern abstraction (much like the Living Theatre's non-linear stagings), Rzewski's more dramatically straightforward reading keeps its structure apparent and puts the work more firmly in the tradition of 18th and 19th century melodramas.

Even when Rzewski is on firmer structural ground - in his Sonata for Solo Piano (1991), for example - his free impulses never fully subside. Within the Sonata's tightly wound, three-movement structure are quotes from 'Ring Around the Rosy' and 'Santa Claus is Coming to Town', as well as 27 variations on 'L'Homme Arme'. Both in his references, and in the way he keeps condensing them within his sections, Rzewski constantly tweaks our notions of past and present.

Hard as it may be to believe, two discs of this collection are devoted to The Road, an epic that Rzewski has been writing since 1995 and is still unfinished. Rzewski calls the work 'a novel', in part because of its inspirations from Tolstoy and Dostoyevsky, in part because he conceived it to be performed by a pianist at home without regards to an audience. In Christian Wolff's superb liner notes, Rzewski calls them 'a collection from which to choose,' which pretty much sums up 'Rzewski Plays Rzewski' as a whole. One disc rings with brilliance, two and the ears already start to numb. Three or more and the senses are already hammered into submission.