Full Idea
Hanslick concluded from the fact that music doesn't express definite feelings like piety, love, joy, or sadness, that it isn't an art of expression.
Gist of Idea
Music is not an expressive art, because it expresses no familiar emotions
Source
report of Eduard Hanslick (The Beautiful in Music [1854]) by Richard Wollheim - Art and Its Objects 48
Book Reference
Wollheim,Richard: 'Art and Its Objects' [Penguin 1975], p.127
A Reaction
Whether music is 'expressive' (which it may not be) should not be confused with whether it is emotional, which it clearly is, even in its coolest examples. Hanslick viewed music as a code, not a language.