by Queen Elizabeth brings before us the sovereign herself, though the person who wears the ruff may have no other circumstance of resemblance; ... it is necessary only that a part of the complexity (the Queen) should be recalled as the ruff-to bring back all the other parts, by the mere principle of contiguity. . . . In like manner we might be able to reduce every case of suggestion association "from direct resemblance to the influence

of mere contiguity."

We might state his illustration this way: ruff + a b c d (abcd meaning a person wearing it) recalls ruff +efgh (efgh meaning Elizabeth), because the thought of Elizabeth and the ruff were in our minds at the same time.

Can Association by Contiguity be Explained by Association by Similarity? - Others explain association by contiguity by association by similarity. The same

example can be used to illustrate their position. They would say, granted that ruff + a b c d recalls ruff +ef g h because there is a ruff in both cases, yet the ruff that Elizabeth wore is not the one we see now. Let R stand for the ruff we see now and R' for the ruff worn by Elizabeth, and we can symbolize the facts in this form: Rabcd recalls R'eƒgh. Stated in this form, they say, it is evident that Rabcd recalls R'efgh because of the likeness between R and R'.

I think we shall agree that the latter have only explained why R recalls R'. To account for the fact that we think of efgh also, I think we must say R′ recalls eƒgh because R′ and efgh were thought of at the same time. In other words, association by contiguity is an ultimate mental law, ultimate because it can not be analyzed into anything simpler.

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FUNDAMENTAL LAW OF ASSOCIATION.

205

We have, then,

Fundamental Law of Association. as our fundamental law of association the following: One thought, idea, or experience tends to recall similar thoughts, ideas, or experiences, and all other thoughts, ideas, or experiences that were in the mind at the same time. Remembering the influence exerted upon association by the apprehension of inner relations, we see that the above law requires qualification: One thought, idea, or experience tends to recall similar thoughts, ideas, or experiences, and all other thoughts, ideas, or experiences that were in the mind at the same time, the latter with a force proportionate to the number and clearness of the inner relations apprehended between them and the attention we bestow upon them.

Explanation of the Association of Ideas. But, after all, what does this so-called law amount to? If we examine it closely, we shall see that all it does is to describe the facts. When we are thinking of one thing, we are likely the next moment to find ourselves thinking of some similar thing, or of something which we have thought of before when we were thinking of that thing. That is what the law states, but as to why it is so, it is as silent as the sphynx. Can we assign a cause for the association of ideas? Can we tell why it is that the thought of one thing tends to recall the thought of some other thing?

Physical Basis. There seems good reason for sup posing that the association of ideas is due to the law of habit in the nervous system. The similarity between the phenomena of habit and association by contiguity is evident at a glance. Now, if we suppose·

as we must

that there is a physical basis for these thoughts or ideas associated by contiguity, we shall see that there is reason for supposing that one thought recalling another thought that has been in the mind before in connection with it, is due to the fact that one brain change tends to excite another brain change which has been active before in connection with it. We have seen that the various parts of the cortex are connected with each other by fibres called association fibres. It is these fibres which are supposed to be the conductors along which the nervous current passes from one part of the cortex to another which has been in a state of excitement at the same time.

Further, if we suppose that similar ideas have their physical basis in the same part of the brain as the evidence requires us to do at least to a certain extent, since it has already been proved, as we have seen, that sensations of sight are localized in a particular part of the cortex we shall be able to form a crude sort of notion of how it happens that thinking of one thing tends to make us think of a similar thing. The thought of the one thing is due to the excitement of some of the same cortical cells whose excitation caused the thought of the preceding thing, and therefore the excitation of the cells corresponding to the thought of one thing causes, by the law of habit, the excitation of the cells corresponding to the thought of the other thing.

Limitations of such Explanations. But if we accept this crude explanation as entirely complete and satisfactory - and it is far from it - there are some facts which neither it nor any other physical explanation has ever made clear. Granted, for example, that the excitation of similar parts

of the brain causes similar thoughts to arise in the mind, how do we know that those thoughts are similar? The existence of similar thoughts is one thing; the consciousness of their similarity is a radically different thing.

But the thorough discussion of these questions is too difficult for such elementary study as ours. If you wish to see the best explanation that has ever been given of the association of ideas, read Professor James's Psychology, and if you wish to see a forcible statement of the limitations of all such explanations, read Professor Ladd's Physiological Psychology.

QUESTIONS ON THE TEXT.

I. Illustrate what is meant by association of ideas from your own experience.

2. Illustrate from your own experience the different kinds of association.

3. What is the difference between logical association and association by contiguity?

4. Explain the different names for association by contiguity.

5. Explain the various reasons why things logically associated tend to recall each other.

6. State the two laws of association, and explain the attempts to derive one from the other.

7. State verbatim the formula in which the two may be stated.

SUGGESTIVE QUESTIONS.

1. Explain ideas in the phrase, association of ideas.

2. A child seeing a snake licking out its tongue, said it was making faces at him. What kind of association was that?

3. I read to-day the following sentence from Goethe: "Take care of the beautiful, and the useful will take care of itself,” and at once thought of Spencer's essay on "What Knowledge is of Most Worth." Why?

4. What kind of associations do children first form?

LESSON XXII.

PERCEPTION.

Knowledge Begins with Sensations.

We have seen

already that all knowledge takes its rise in sensation. The mental history of every human being begins with its first sensation. Before the first sensation, the only difference between a human being and any other growing thing-a tree, for instance- so far as mind is concerned, consists in the fact that the former possesses the potentiality of mind. This potentiality first begins to become actuality when the human being experiences its first sensations.

Sensations Exist before they are Known. But although knowledge takes its rise in sensation, it by no means follows that the first experience of sensations constitutes the beginning of knowledge. If we consider what knowledge is, we shall see that, in the nature of the case, the mind must have sensations before it knows it has them. I do not mean merely that a fact must exist in order to be known. That, of course, is true of sensations, but more than that is true. Sensations not only must exist in order to be known, but they may exist — and often do - for a considerable period before they are known; and I think, if we realize what knowledge is, we shall see that in the nature of the case this must be so.