The teacher can formulate his function to himself therefore in terms of ‘association’ as well as in terms of ‘native and acquired reaction.’  It is mainly that of building up useful systems of association in the pupil’s mind.  This description sounds wider than the one I began by giving.  But, when one thinks that our trains of association, whatever they may be, normally issue in acquired reactions or behavior, one sees that in a general way the same mass of facts is covered by both formulas.

It is astonishing how many mental operations we can explain when we have once grasped the principles of association.  The great problem which association undertakes to solve is, Why does just this particular field of consciousness, constituted in this particular way, now appear before my mind? It may be a field of objects imagined; it may be of objects remembered or of objects perceived; it may include an action resolved on.  In either case, when the field is analyzed into its parts, those parts can be shown to have proceeded from parts of fields previously before consciousness, in consequence of one or other of the laws of association just laid down.  Those laws run the mind:  interest, shifting hither and thither, deflects it; and attention, as we shall later see, steers it and keeps it from too zigzag a course.

To grasp these factors clearly gives one a solid and simple understanding of the psychological machinery.  The ‘nature,’ the ‘character,’ of an individual means really nothing but the habitual form of his associations.  To break up bad associations or wrong ones, to build others in, to guide the associative tendencies into the most fruitful channels, is the educator’s principal task.  But here, as with all other simple principles, the difficulty lies in the application.  Psychology can state the laws:  concrete tact and talent alone can work them to useful results.

Meanwhile it is a matter of the commonest experience that our minds may pass from one object to another by various intermediary fields of consciousness.  The indeterminateness of our paths of association in concreto is thus almost as striking a feature of them as the uniformity of their abstract form.  Start from any idea whatever, and the entire range of your ideas is potentially at your disposal.  If we take as the associative starting-point, or cue, some simple word which I pronounce before you, there is no limit to the possible diversity of suggestions which it may set up in your minds.  Suppose I say ‘blue,’ for example:  some of you may think of the blue sky and hot weather from which we now are suffering, then go off on thoughts of summer clothing, or possibly of meteorology at large; others may think of the spectrum and the physiology of color-vision, and glide into X-rays and recent physical speculations; others may think of blue ribbons, or of the blue flowers on a friend’s hat, and proceed on lines of personal reminiscence.  To others, again, etymology and linguistic thoughts may be suggested; or blue may be ‘apperceived’ as a synonym for melancholy, and a train of associates connected with morbid psychology may proceed to unroll themselves.