Like it or not, TJ Clark's The Painting of Modern Life nowadays stands as a classic when it comes to look at late 19th-century French painting and think about art in terms of modernity, in relation with the avant-garde, bourgeois culture and values, and the urban environment.
TJ Clark's analysis is heavily connotated with Marxist theory and ways of thinking, which directs demonstrations and arguments in stimulating ways - if nonetheless slightly predictable ones.
In any case, if you are interested in Manet, and the representation of modernity, this is one book which cannot be ignored and will have to be read, if only for the sake of the literature review.