Abstract Aesthetic theories of art have always had trouble with nonperceptual artworks. James Shelley’s solution of broadening the notion of perception to cover properties that are directly felt is incomplete, until we specify what kind of response to a given property suffices to qualify it as aesthetic. I argue that all aesthetic properties are inherently evaluative and always prompt a positive response in the perceiver, since they are the outcome of an unpredictable and successful interpenetration of formal and semantic elements. An aesthetic definition can legitimately deny that conceptual works are art to the extent that they are not able to formally support the aesthetic qualities usually attributed to them, as is shown by their lack of compliance with the acquaintance principle, while at the same time the definition does not run the risk of undermining the aesthetic status of literature, on which it sheds new light.