which Fig. 4 is a cross section. The mutual relations of the center and periphery are the same in both.

There remains another diagram which can be made useful in educational thinking, and which is intended to illustrate a definition given by Professor James: "The mind is the medium upon which the manifold processes in the brain combine their effects." This formula I have illustrated by a diagram of a storage battery charged from a group of galvanic cells [Fig. 6]. The four large cells, which constitute the storage battery, stand as the symbol of the mind; the group of smaller cells, generating the electricity by chemical action, represent the manifold processes in the brain. The same diagram might be used to symbolize the relations of the manifold processes in the general nervous system, to the brain, which certainly stores these up, and in so doing becomes a reservoir of force. Thus the manifold impressions to which the child is subjected are constantly being unified in the brain, and, by their accumulation at this focus, are serving for the generation of force.

FIG. 5.

FIG. 6.

To secure an abundant generation of force is the second. fundamental aim of education. The great method in nature for the generation of force is the concentration, in as narrow

an area as possible, of impressions derived from a very wide area. The most striking-I might say the most tremendousillustration of this method is furnished by the germ cell. Here an enormous amount of antecedent impressions, tendencies and potentialities, physical, mental, and social, are concentrated upon a point of matter just barely perceptible. A correlatively immense amount of force is produced, sufficient indeed to sustain the germ throughout its entire career of development [see Fig. 7]. Thus the more completely the child's mind unifies the impressions impinging on it, the more mental power results. Conversely, when impressions, though multiple, are not unified, but impinge on the mind in a frag

mentary, desultory mass, then no single thought results, and power fails to be generated.

This statement may be paraphrased in terms of brain processes thus: Every thought or activity of consciousness is associated with the excitation of some tract of nerve-tissue in the brain. The fusion of such thoughts into a single conception implies that diffused cerebral excitations have been converged into a single massive impulse, which corresponds to the activity of the brain in its totality.

If we analyze the first piece of knowledge which we are imparting to the child-the properties of the wooden cube-we shall encounter three grades of fusion. In the first grade rays. of light from the cube are brought to a focus at a certain part of the retina, the point of distinct vision, called the macula

lutea or yellow spot. This focusing necessitates fixation of the eyes by a voluntary effort on the part of the child-effort which constitutes his first act of attention. After this has been effected, color impressions from the retina are transmitted to the brain, and together with them, other impressions from the muscles employed in the fixation of the eye, and in the successive fixations required to bring successive segments of the cube's outline at the ocular focus. There is a certain area of the brain, on its posterior or occipital lobe, known as the visual center, whose excitation seems essential to the act of vision. It is probable that the two sets of impressions I have mentioned as arising from the eyes, meet at this visual center and there fuse together. This is the second grade of fusion, and results for the first time in a distinct perception of the object, the cube. The fusion of rays in the retinal image

V. C.

FIG. 8.

took place below the level of consciousness. The perception rises just above that level. In other words, the first thing of which the child is conscious in regard to the cube is that he perceives it. This perception constitutes a new thought or phase of consciousness. [See Fig. 8.]

In a third grade of fusion, perceptions of individual objects are combined into the concept of a class, or a number of simple ideas, or propositions, are combined into a complex conception. Where, however, this third combination takes place, we do not at all know.

Upon the basis of the facts above mentioned, the following proposition may be constructed: When the brain processes involved in visual perceptions-as of the wooden cube-have been frequently repeated; when they have been associated with brain processes involved in tactual perceptions of the same cube; when these perceptions and processes excited by the cube have coexisted with perceptions and processes excited by other

objects, and revived by memory in consciousness for comparison; then a state of consciousness is aroused which may be called an internal perception. This is a single pulse of thought, but it embraces, as objects, the multiple details of the previous states. They therefore may be said to be unified in it.

It is possible that this internal perception of self-consciousness, this single pulse of unifying thought, corresponds to a total excitation of the brain. And that is why injury of any part of the brain, and even of a very limited part, is liable to be followed by a defect of consciousness, or even by its total loss. What is important to remember is, the necessity that perceptions should in some way converge upon a focus in order to originate a definite conception in consciousness, and that this focusing process seems to be a continuation of those already described at the retina and at the visual center of the brain. The two lower processes of focusing I have illustrated in the diagram [Fig. 8]. The two other processes I have left unillustrated, because of the profound mystery which surrounds them; mystery which it is not well either to belittle or slur over with cheap explanations.

When ideas are to be combined in a single conception, we can always combine statements into a single proposition, and express this graphically in a diagram. All the diagrams I have used to illustrate my own propositions serve, I hope, to show this fact. In addition, I will present a few more designed for purposes of specific school instruction. Thus Fig. 9 condenses, 1. Molar motion of percussion generates molecular motion that we call heat.

2. Molecular motions of chemical action constitute heat, and have a mechanical value, i. e., in reference to molar motion or masses.

under a single visual symbol, several propositions in physics. In Fig. 10 an apparently reverse process is followed. A single

proposition is taken, and shown to be in fundamental agreement with several other propositions, which to superficial inspection seem widely removed. This is the proposition. Electricity flows from a body of high potential, into a body of low potential. These propositions all condense into this single conception: Differentiation passes into equilibrium, and during the transition, force is evolved.

This brief suggestion of a method whereby all items of knowledge are constantly being fused into single concep