There is clearly a paradox at work here: how can sounds that are unheard, that are silent, be more pleasing to the ear than those that can be heard? In invoking this tension between the sounds of music and its corresponding visual representation, Keats points to the role of the imagination in the aesthetic experience of ancient Greek vase-painting. Images of musical performances are sweeter precisely because they cannot be heard. The audience must instead imagine the sounds, creating an infinite variety of melodic possibilities that emanate from the image. Permanently captured in a state of continued poetic performance, the pipes play on, repeatedly offering to the viewer the opportunity to imagine the acoustic sounds that fill the visual scene.