In order to be used as a single unit, the enormous sum integrated by a concept has to be given the form of a single, specific, perceptual concrete, which will differentiate it from all other concretes and from all other concepts. This is the function performed by language. Language is a code of visual-auditory symbols that serves the psycho-epistemological function of converting concepts into the mental equivalent of concretes. Language is the exclusive domain and tool of concepts. Every word we use (with the exception of proper names) is a symbol that denotes a concept, i.e., that stands for an unlimited number of concretes of a certain kind.
The first words a child learns are words denoting visual objects, and he retains his first concepts visually. Observe that the visual form he gives them is reduced to those essentials which distinguish the particular kind of entities from all others — for instance, the universal type of a child’s drawing of man in the form of an oval for the torso, a circle for the head, four sticks for extremities, etc. Such drawings are a visual record of the process of abstraction and concept-formation in a mind’s transition from the perceptual level to the full vocabulary of the conceptual level.
There is evidence to suppose that written language originated in the form of drawings — as the pictographic writing of the Oriental peoples seems to indicate. With the growth of man’s knowledge and of his power of abstraction, a pictorial representation of concepts could no longer be adequate to his conceptual range, and was replaced by a fully symbolic code.
The process of forming a concept is not complete until its constituent units have been integrated into a single mental unit by means of a specific word. The first concepts a child forms are concepts of perceptual entities; the first words he learns are words designating them. Even though a child does not have to perform the feat of genius performed by some mind or minds in the prehistorical infancy of the human race: the invention of language — every child has to perform independently the feat of grasping the nature of language, the process of symbolizing concepts by means of words.
Even though a child does not (and need not) originate and form every concept on his own, by observing every aspect of reality confronting him, he has to perform the process of differentiating and integrating perceptual concretes, in order to grasp the meaning of words. If a child’s brain is physically damaged and unable to perform that process, he does not learn to speak.
Learning to speak does not consist of memorizing sounds — that is the process by which a parrot learns to “speak.” Learning consists of grasping meanings, i.e., of grasping the referents of words, the kinds of existents that words denote in reality. In this respect, the learning of words is an invaluable accelerator of a child’s cognitive development, but it is not a substitute for the process of concept-formation; nothing is.
Words transform concepts into (mental) entities; definitions provide them with identity. (Words without definitions are not language but inarticulate sounds.)
It is often said that definitions state the meaning of words. This is true, but it is not exact. A word is merely a visual-auditory symbol used to represent a concept; a word has no meaning other than that of the concept it symbolizes, and the meaning of a concept consists of its units. It is not words, but concepts that man defines — by specifying their referents.