If there is any one thing in the world that seems utterly chaotic, it is the way in which the mind wanders from one subject of thought to another. It requires but a moment for it to flash from New York to San Francisco, from San Francisco to Tokio, and around the globe. Yet mental processes are as law-abiding as anything else in Nature.

So much is this true, that if we knew every detail of your past experience from your first infantile sensation, and knew also just what you are thinking of at the present moment, we could predict to a mathematical certainty just what ideas would next appear on the kaleidoscopic screen of your thoughts. This is due to laws that govern the association of ideas.

These laws are, in substance, that the way in which judgments and ideas are classified and stored away, and the order in which they are brought forth into consciousness depends upon what other judgments and ideas they have been associated with most habitually, recently, closely and vividly.

There are, therefore, four Prime Laws of Association—the Law of Habit, the Law of Recency, the Law of Contiguity and the Law of Vividness.

Every idea that can possibly arise in your thoughts has its vast array of associates, to each of which it is linked by some one element in common. Thus, you see or dream of a yellow flower, and the one property of yellowness links the idea of that flower with everything you ever before saw or dreamed of that was similarly hued.

But the yellow-flower thought is not tied to all these countless associates by bonds of equal strength. And which associate shall come next to mind is determined by the four Prime Laws of Association.

The Law of Habit requires that frequency of association be the one test to determine what idea shall next come into consciousness, while the Laws of Recency, Contiguity and Vividness emphasize respectively recency of occurrence, closeness in point of space and intensity of impression. Which law and which element shall prevail is all a question of degree.

The most important of these laws is the Law of Habit. In obedience to this law, the next idea to enter the mind will be the one that has been most frequently associated with the interesting part of the subject you are now thinking of.

The sight of a pile of manuscript on your desk ready for the printer, the thought of a printer, the word "printer," spoken or printed, calls to mind the particular printer with whom you have been dealing for some years.

The word "cocoa," the thought of a cup of cocoa, the mental picture of a cup of cocoa, may conjure with it not merely a steaming cup before the mind's eye and the flavor of the contents, but also a daintily clad figure in apron and cap bearing the brand of some well-known cocoa manufacturer.

If a typist or pianist has learned one system of fingering, it is almost impossible to change, because each letter, each note on the keyboard is associated with the idea of movement in a particular finger. Constant use has so welded these associations together that when one enters the mind it draws its associate in its train.

Test the truth of these principles for yourself. Try them out and see whether the elements of habit, contiguity, recency and intensity do not determine all questions of association.

If you wanted to buy a house, what local subdivision would come first to your mind, and why? If you were about to purchase a new tire for your automobile or a few pairs of stockings, what brand would you buy, and why? When you think of a camera or a cake of soap, what particular make comes first to your mind? When you think of a home, what is the mental picture that rises before you, and why?

Whatever the article, whether it be one of food or luxury or investment, or even of sentiment, you will find that it is tagged with a definite associate—a name, a brand, or a personality characterized by frequency, recency, closeness or vividness of presentation to your consciousness.

The grouping together of sensations into integral ideas is one step in the complicated mental processes by which useful knowledge is acquired. But the associative processes go much beyond this.

We also compare the different objects of present and past experience. We carefully and thoroughly catalogue them into groups, divisions and subdivisions for convenient and ready reference. This we do by the processes of memory, of association and of discrimination, previously referred to.

Through these processes our knowledge of the world, derived from the whole vast field of experience, is unified and systematized. Through these processes is order realized from chaos. Through these processes it comes about that not only individual thought, but the communication of thought from one person to another, is vastly simplified. Language is enabled to deal with ideas instead of with isolated sense-perceptions. The single word "horse" suffices to convey a thought that could not be adequately set forth in a page-long enumeration of disconnected sense-perceptions.

The associative process covers a wide range. It includes, for example, not only the simple definition of an aggregate of sense-perceptions, as "horse" or "cow"; it includes as well the inferential process of abstract reasoning.

The only real difference between these widely diverse mental acts, one apparently so much less complicated and profound than the other, is that the former involves no act of memory, while the latter is based wholly on sensory experiences of the past.

Abstract reasoning is merely reasoning from premises and to conclusions which are not present to our senses at the time.