A Classifying Judgment associates and compares present and past sense-perceptions. It is the final process in the production of that marvel of the mind, the "idea."

The simple perception of a sensation unaccompanied by any other mental process is something that never happens to an adult human being.

In the infant's mind the arrival of a sense-impression arouses only a perception, a consciousness of the sense-impression. In the mind of any other person it awakens not only this present consciousness but also the associated memories of past experiences.

Upon the slumbering mind of the newborn babe the very first message from the sense-organs leaves its exquisite but indelible impress. The next sense-perception is but part of a state of consciousness, in which the memory of the first sense-perception is an active factor. This is a higher type of mental activity. It is a something other and more complex than the mere consciousness of a sensory message and the decision as to its source.

The moment, then, that we get beyond the first crude sense-perception consciousness consists not of detached sensory images but of "ideas," the complex product of present sense-perceptions, past sense-perceptions and the mental processes known to psychology as association and discrimination.

Every concrete conception or idea, such as "horse," "rose," "mountain," is made up of a number of associated properties. It has mass, form and various degrees of color, light and shade. Every quality it possesses is represented by a corresponding visual, auditory, tactual or other sensation.

Thus, your first sense-perception of coffee was probably that of sight. You perceived a brown liquid and your causal judgment explained that this sense-perception was the result of something outside of your body. Standing alone, this causal judgment meant very little to you, so far as your knowledge of coffee was concerned. So also the causal judgment that traced your sense of the smell of coffee to some object in space meant little until it was added to and associated with your eye-vision of that same point in space. And it was only when the causal judgment explaining the taste of coffee was added to the other two that you had an "idea" of what coffee really was.

When you look at a building, you receive a number and variety of simultaneous sensations, all of which, by the exercise of a causal judgment, you at once ascribe to the same point in space. From this time on the same flowing together of sensations from the same place will always mean for you that particular material thing, that particular building. You have a sensation of yellow, and forthwith a causal judgment tells you that something outside of your body produced it. But it would be a pretty difficult matter for you to know just what this something might be if there were not other simultaneous sensations of a different kind coming from the same point in space. So when you see a yellow color and at the same time experience a certain familiar taste and a certain softness of touch, all arising from the same source, then by a series of classifying judgments you put all these different sensations together, assign them to the same object, and give that object a name—for example, "butter."

This process of grouping and classification that we are describing under the name of "classifying judgments" is no haphazard affair. It is carried on in strict compliance with certain well-defined laws.

These laws prescribe and determine the workings of your mind just as absolutely as the laws of physics control the operations of material forces.

While each of these laws has its own special province and jurisdiction, yet all have one element in common, and that is that they all relate to those mental operations by which sense-perceptions, causal judgments, and even classifying judgments, past, present and imaginative, are grouped, bound together, arranged, catalogued and pigeonholed in the archives of the mind.

These laws, taken collectively, are therefore called the Laws of Association.