Gabriela Montero @ City Halls, Glasgow

The theme for Gabriela Montero's improvisational encore was not promising: an audience member suggested It Ain't Necessarily So from Porgy and Bess, only managing to sing a single line. Yet, after picking out the line on the piano, Montero launched into an improvisation that ignored the song's jazz influences (for the most part), and toured around the pianist's knowledge of classical, romantic and rag-time motifs.

Improvisation is more readily associated with jazz - Adorno, one of those Cultural Marxists who have ruined everything moaned that it gave the illusion of change without ever departing from the theme. It's a political reading (jazz is like a false consciousness, pretending to be radical but relying heavily on existing structures). Montero's deliberate inclusion of improvisation in the concert hall answers his rather disappointing complaint.

This improvisation was a handy spot of musical history - at least for a character like me, who has a relatively shonky grasp of the history of western orchestral music. Kicking off with something that sounded like Bach - ordered, trilling, serious and maybe a little too pleased with itself, Montero soon drifted into more expansive, lyrical and romantic territory. Yet, as Adorno says, she never lost the theme... and that is the point. Putting Gershwin through his paces, pointing out how recognisable moods and atmospheres define the style, Montero both reveals her skills and points out how music is determined by its references to other music.

That last phrase might not be clear - that it, I call a piece 'classical'

or 'romantic' because I recognise it in relation to other romantic pieces. 

Then she went rag-time on it. Syncopated beats, I believe. 

Most of the audience had fun recognising It's Ain't... re-emerging from her runs. I went into the fantasy land of semiotics and thought about how clever I am. That wasn't Montero's fault, but I am learning about this music stuff.