In different men the impulse to know bears different relationships to the rest of life. It sometimes seems self-impelled, and again palpably inspired by a motive beyond itself. In some form, however, it winds itself into every action of our mental faculties, and no province of life appears untouched by this craving of the mind. Nevertheless to know is not the whole matter; for with knowledge comes appetition or aversion, admiration or contempt, love or abhorrence; and other impulses--emotional, desiderative, loving--impel the human creature to realize its nature in states of heightened consciousness that are not palpable modes of knowing, though they may be replete with all the knowledge that the man has gained. These ultimate cravings which we recognize in ourselves, inspired mediaeval thought. Its course, its progress, its various phases, its contents and completed systems, all represent the operation of human faculty pressing to expression and realization under the accidental or “historical” conditions of the mediaeval period. We may be sure that many kinds of human craving and corresponding faculty realized themselves in mediaeval philosophy, theology, piety and mysticism--the last a word used provisionally, until we succeed in resolving it into terms of clearer significance. And we also note that in these provinces, realization is expression. Every faculty, every energy, in man seeks to function, to realize its power in act. The sheer body--if there be sheer body--acts bodily, operates, and so makes actual its powers. But those human energies which are informed with mind, realize themselves in ardent or rational thought, or in uttered words, or in products of the artfully devising hand. All this clearly is expression, and corresponds, if it is not one and the same, with the passing of energy from potency to the actuality which is its end and consummation. Thus love, seeking its end, thereby seeks expression, through which it is enhanced, and in which it is realized. Likewise, impelled by the desire to know, the faculties of cognition and reason realize themselves in expression; and in expression each part of rational knowledge is clarified, completed, rendered accordant with the data of observation and the laws or necessities of the mind.