Sonata, what do you want of me?

So asked Fontenelle, according to Rousseau. His frustration is one that I have shared. It is hard to articulate the content of abstract music in a way that could explain why it matters so much, at least to some of us, and annoying to be left with nothing to say.

This plight is addressed with brevity, and an apt historicism, in a recent book by Mark Evan Bonds. Music as Thought recounts the valorization of instrumental music, and the symphony in particular, at the turn of the 18th century. In 1790, Kant could dismiss non-vocal music as "more pleasure than culture". By 1810, Hoffman would write, in a celebrated review, that Beethoven's Fifth "open[s] up to us the realm of the monstrous and immeasurable."

What happened in between, according to Music as Thought, was the aesthetics of post-Kantian idealism, in Fichte, Schelling and others. If abstract music conveys the infinite or the Absolute, or a unity of subject and object that lies beyond our conceptual grasp, there is no embarrassment in our inability to capture it in words. The philosophers and critics – not the musicians – could thus invent a new way of listening and, in doing so, a new kind of music.

Even if one is sympathetic to the need for generic and thus historical context in the explanation of art, there is something puzzling in this account. If it is right, we face a problem of belief – or worse – when we aspire to listen without anachronism. It is not just that we may not accept the metaphysics of idealism; we may not even attach a sense to the putative thoughts that Hoffman and others took Beethoven's symphonies to express.

Nor does Music as Thought say very much about how to interpret specific works. In part because the philosophy is so lightly sketched, what we get is not a map of the conventions of the idealist symphony against which particular symphonies stand out in relief, but something more like a reading of various works taken together – an approach that is "generic" in the negative sense.

This is only to say that the book is incomplete: it is a provocation to further thought. One of its best ideas is about the indeterminacy of abstract music. The facts of production and reception are sufficiently messy that they may not fix upon the form of a given piece, a single generic context. In an ingenious coda, this argument is applied to the musical formalism of Eduard Hanslick. Rather than divining the essence of abstract music, we might regard him as proposing – inadvertently, perhaps – yet another way in which it can be heard. The question is not what the sonata wants of us, but what we want of it.