“Though the actual developments in many arts may seem to be leading us away from the idea that a work of art is primarily its content, the idea still exerts an extraordinary hegemony. I want to suggest that this is because the idea is now perpetuated in the guise of a certain way of encountering works of art thoroughly ingrained among most people who take any of the arts seriously. What the overemphasis on the idea of content entails is the perennial, never consummated project of interpretation. And, conversely, it is the habit of approaching works of art in order to interpret them that sustains the fancy that there really is such a thing as the content of a work of art.”
Sontag’s classic essay of 1964. The link is here.