Definition of Association . In the foregoing chapters reference has been repeatedly made to the principle of "association of ideas"; indeed some knowledge of such a principle is so generally implied in the affairs of life that its familiarity has been assumed. The truth that things owe their character to their associations, that men are influenced by their associates, is only a broader application of the law which takes its rise in the mental life.
The conditions under which the revival of mental images in general is possible have been stated. It proceeds upon a renewal of the nervous action which accompanied the first perception, and the reinstatement of the original apperceptive act with a sufficient intensity and duration. This, however, does not suffice to inform us what it is that gives specific direction to the flow of reproduced states. Why is it that among an infinite number of possible reproductions a particular representation rather than others is revived? This question indicates the true function of association, which is the progressive revival of particular mental states. The fact of association may also be defined as the relation between revived states of consciousness, whereby continuity of successive representation is secured in the form of new integrated states. This we must fully explain.____________________
Cf. my Handbook of Psychology, vol. i chap. xi.