Ayn Rand had a little to say on the subject. She wrote books about Esthetics.
Art
Art is a selective re-creation of reality according to an artist’s metaphysical value-judgments. Man’s profound need of art lies in the fact that his cognitive faculty is conceptual, i.e., that he acquires knowledge by means of abstractions, and needs the power to bring his widest metaphysical abstractions into his immediate, perceptual awareness. Art fulfills this need: by means of a selective re-creation, it concretizes man’s fundamental view of himself and of existence. It tells man, in effect, which aspects of his experience are to be regarded as essential, significant, important. In this sense, art teaches man how to use his consciousness. It conditions or stylizes man’s consciousness by conveying to him a certain way of looking at existence.
“Art and Cognition,”
The Romantic Manifesto, 45
By a selective re-creation, art isolates and integrates those aspects of reality which represent man’s fundamental view of himself and of existence. Out of the countless number of concretes—of single, disorganized and (seemingly) contradictory attributes, actions and entities—an artist isolates the things which he regards as metaphysically essential and integrates them into a single new concrete that represents an embodied abstraction.
For instance, consider two statues of man: one as a Greek god, the other as a deformed medieval monstrosity. Both are metaphysical estimates of man; both are projections of the artist’s view of man’s nature; both are concretized representations of the philosophy of their respective cultures.
Art is a concretization of metaphysics.
Art brings man’s concepts to the perceptual level of his consciousness and allows him to grasp them directly, as if they were percepts.
This is the psycho-epistemological function of art and the reason of its importance in man’s life (and the crux of the Objectivist esthetics).
“The Psycho-Epistemology of Art,”
The Romantic Manifesto, 19