certain shapes as triangles or certain colors as red when a triangular shape or a red patch is not perceptually present and actually
perceived.^3What is the nature of the immense intellectual leap that takes place with the development in man of the ability to
form concepts? What is the nature of the ascent from the ability to perceive various green-colored objects to the
ability to form the concept "green"—to move from the perception of individual chairs to the concept "chair"—to
move from the perception of individual men to the concept "man"?
To appreciate the nature of the tremendous increase of intellectual power made possible by man's conceptualizing
ability, it is necessary to realize the extreme limitations of an exclusively perceptual form of awareness. The
number of units that any consciousness—human or animal—can hold in its field of awareness at any given
moment, is necessarily small. A consciousness that is restricted only to those sensible particulars it can immediately
perceive is severely restricted in its ability to accumulate or expand its knowledge. This is the state of all animals
under man.
The ascent to the conceptual level of consciousness entails two related factors: the ability to categorize numerous
particulars into groups or classes, according to a distinguishing characteristic(s) they exhibit in common —and the
ability to develop or acquire a system of symbols that represents these various classes, so that a single symbol, held
in a man's mind, can stand for an unlimited number of particulars.
The method of classification is concept-formation. The system of symbols is language.
By way of illustration, let us consider one of the first and simplest concepts a child forms—that of "chair." The first
stage consists of his perceptual recognition that several objects are similar, similar specifically in shape, and are
different from all other objects in regard to that characteristic. He is aware of that similarity on a visual, nonverbal
level, and his mind gropes for some way to hold that awareness in permanent form. The first form in which that
awareness is retained is a vague image, an image that omits many of the differences that exist among the chairs that
he has perceived (such as, say, color) and retains an approximation of the essential