Herbart borrowed his con- cept of idea from the empiricists. That is, he viewed ideas as the remnants of sense impressions. Fol- lowing Leibniz, however, he assumed that ideas (like monads) contained a force or energy of their own, and the laws of association were, therefore, not necessary to bind them. Herbart’s system has been referred to as psychic mechanics because he believed that ideas had the power to either attract or repel other ideas, depending on their compatibil- ity. Ideas tend to attract similar or compatible ideas, thus forming complex ideas. Similarly, ideas expend energy repelling dissimilar or incompatible ideas, thus attempting to avoid conflict. According to Herbart, all ideas struggle to gain expression in con- sciousness, and they compete with each other to do so. In Herbart’s view, an idea is never destroyed or completely forgotten; either it is experienced con- sciously or it is not. Thus, the same idea may at one time be given conscious expression and at another time be unconscious.
Although ideas can never be completely destroyed, they can vary in intensity, or force. For Herbart, intense ideas are clear ideas, and all ideas attempt to become as clear as possible. Ideas in consciousness are bright and clear; unconscious ideas are darker and more obscure. Herbart used the term self-preservation to describe an idea’s ten- dency to seek and maintain conscious expres- sion. That is, each idea strives to preserve itself as intense, clear, and conscious. This tendency toward self-preservation naturally brings each idea into conflict with other, dissimilar ideas that are also seeking conscious expression. Thus, Herbart viewed the mind as a battleground where ideas struggle with each other to gain conscious expres- sion. When an idea loses its battle with other ideas, rather than being destroyed, it momentarily loses some of its intensity (clarity) and sinks into the unconscious.