The development of human cognition starts with the ability to perceive things, i.e., entities. Of man's five cognitive senses, only two provide him with a direct awareness of entities: sight and touch. The other three senses—hearing, taste and smell—give him an awareness of some of an entity's attributes (or of the consequences produced by an entity): they tell him that something makes sounds, or something tastes sweet, or something smells fresh; but in order to perceive this something, he needs sight and/or touch.
The concept "entity" is (implicitly) the start of man's conceptual development and the building-block of his entire conceptual structure. It is by perceiving entities that man perceives the universe. And in order to concretize his view of existence, it is by means of concepts (language) or by means of his entity-perceiving senses (sight and touch) that he has to do it.
Music does not deal with entities, which is the reason why its psycho-epistemological function is different from that of the other arts, as we shall discuss later.
The relation of literature to man's cognitive faculty is obvious: literature re-creates reality by means of words, i.e., concepts. But in order to re-create reality, it is the sensory-perceptual level of man's awareness that literature has to convey conceptually: the reality of concrete, individual men and events, of specific sights, sounds, textures, etc.
The so-called visual arts (painting, sculpture, architecture) produce concrete, perceptually available entities and make them convey an abstract, conceptual meaning.
All these arts are conceptual in essence, all are products of and addressed to the conceptual level of man's consciousness, and they differ only in their means. Literature starts with concepts and integrates them to percepts- painting, sculpture and architecture start with percepts and integrate them to concepts. The ultimate psycho-epistemological function is the same: a process that integrates man's forms of cognition, unifies his consciousness and clarifies his grasp of reality.
Ayn Rand, Art and Cognition, The Objectivist, p. 1010