The present work addresses the aesthetic philosophy of Eduard Hanslick in order to demarcate it as an epistemological approach to music and a paradigmatic case for musical autonomy. The epistemological assumptions that guided the work On the Musically Beautiful and its most likely influences were analyzed. We conclude by presenting musical idea as an epistemological formulation strongly influenced by positivism and as a qualifying principle of autonomous musical perception. We add to this conclusion a disambiguation with Kant›s concept of aesthetic (...) idea. (shrink)