What is the main theme in the novel, City of the Mind?

One major theme in this novel is the city of London itself. Lively foregrounds and personifies the city, describing it as "throbbing" and "pulsing" and portraying it as being fueled by the energies of the myriad individuals who inhabit it. This impression of the city's richness and texturedness is in part effected by the frequent cataloguing of the sights, sounds, and smells that bombard Matthew on his daily traversings of the city: the various ethnic restaurants, the cacophony of languages, the pastiche of architectural styles from different eras.