You don't usually associate Daniel Barenboim with Bach. But his performance of the first book of The Well-Tempered Clavier was a shattering experience, making this huge cycle of 24 preludes and fugues a vivid emotional journey.

Barenboim's approach to this music was unashamedly personal: he was not afraid to add his own ornamentation, or to thicken the textures of the music by adding resonant lower octaves to Bach's original lines. Instead of focusing on the crystalline detail of every level of Bach's counterpoint, he was more concerned to give each piece a definite expressive shape. The C sharp minor fugue was a case in point. From a four-note chromatic theme, Bach creates a structure of tortuous complexity, and Barenboim made the whole fugue a single, overwhelming increase in intensity and power until the music's climax in a crunching dissonance. There was a symphonic scale to his performance of individual pieces, but even more impressive was the way he shaped the whole cycle as a series of ebbs and flows of tension.

Barenboim's range of touch encompassed astonishing delicacy as well as strength: the sarabande of the D sharp minor prelude had a gossamer lightness, and the obsessive music of the B minor prelude had a shadowy strangeness. Bach never intended these pieces for public performance, but Barenboim turned them from pedagogical exercises into grand display pieces. In the later preludes and fugues, he created a mysterious sense of momentum, from the volcanic dance of the G major fugue to the improvisational fantasy of the B flat major prelude and the monumental power of the final fugue in B minor. Not only was this Barenboim's most concentrated playing of the whole cycle, it was also the culmination of Bach's compositional brilliance, a structure of unbelievable intricacy wrought from a single, simple theme.