"Tönend bewegte Formen sind einzig und allein Inhalt und Gegenstand der Musik. (Music consists entirely and exclusively of forms set in motion through sound.)"
Eduard Hanslick, Vom Musikalisch-Schönen (On the Musically Beautiful)
"Most forms of art which are said to express emotion are also representational. They describe, refer to, or depict the world. Moreover, it is difficult to see how emotions can be expressed in the absence of representation. Every emotion requires an object: fear is a fear of something, anger is anger about something. We can distinguish emotions and classify them only because we can distinguish and classify their (intentional) objects; and we can do this only because we can identify the thoughts through which those objects are defined. In this case, it is difficult to see how a nonrepresentational art such as music can really have a genuine expressive content. It would be impossible to describe that content, since its object could never be identified. Hence it is impossible to give substance to the claim (which might indeed be plausible in the case of poetry or painting) that music serves as a means for communicating emotion."
Roger Scruton, "Analytical Philosophy and the Meaning of Music," The Journal of Aesthetics and Art Criticism 46 (1987): 172.Scruton goes on to proffer an answer to Hanslick in that article, and he constructs a comprehensive philosophy of music in his book, The Aesthetics of Music. In an article entitled "Aesthetic Amputations: Absolute Music and the Deleted Endings of Hanslick's Vom Musikalisch-Schönen," Mark Evan Bonds (whose translation I have borrowed for the quote above) discusses some apparent inconsistencies in Hanslick's thought, exemplified by text deleted from his treatise which shows signs of influence by the Naturphilosophen as well as a similarity to certain ideas of Schopenhauer.
Scruton also discusses "absolute music" in an article for Grove Music Online (the book to read is Dahlhaus's The Idea of Absolute Music):
"Attempts by the advocates of absolute music to answer those questions [regarding understanding in music] have centered on two ideas: objectivity and structure. Their arguments have been presented in this century most forcefully by the Austrian theorist Heinrich Schenker and by Stravinsky. Music becomes absolute by being an ‘objective’ art, and it acquires objectivity through its structure. To say of music that it is objective is to say that it is understood as an object in itself, without recourse to any semantic meaning, external purpose or subjective idea. It becomes objective through producing appropriate patterns and forms. These forms satisfy us because we have an understanding of the structural relations which they exemplify. The relations are grasped by the ear in an intuitive act of apprehension, but the satisfaction that springs therefrom is akin to the satisfaction derived from the pursuit of mathematics. It is not a satisfaction that is open to everyone. Like mathematics it depends on understanding, and understanding can be induced only by the establishment of a proper musical culture.”A related view comes from a much different source. Physicist David Deutsch argues for objectivity in art in his recent book, The Beginning of Infinity:
"In some [art forms], it is especially hard to express in words the explanation of the beauty in a particular work of art, even if one knows it, because the relevant knowledge is itself not expressed in words---it is inexplicit. No one yet knows how to translate musical explanations into natural language. Yet when a piece of music has the attribute ‘displace one note and there would be diminishment’ there is an explanation: it was known to the composer, and it is known to the listeners who appreciate it. One day it will be expressible in words." (365-6)
“Expression is conveying something that is already there, while objective progress in art is about creating something new. Also, self-expression is about expressing something subjective, while pure art is objective. For the same reason, any kind of art that consists solely of spontaneous or mechanical acts, such as throwing paint on to a canvas, or of pickling sheep, lacks the means of making artistic progress, because real progress is difficult and involves many errors for every success.” (366-7)