single thing as standard to which all other things of the same kind are then compared. Logically, the choice is arbitrary, but certain particular selections are made for the sake of the simplicity, elegance, and usefulness of the solutions which result from them.
PSYCHOLOGICAL.
By the creative imagination Professor Ribot means the power of producing mental images, for the most part motor, which realize themselves in the actual production of their appropriate bodily movements, both molar and molecular. Indeed, the motor image is but the actual bodily movement in an incipient stage, and may be either productive or inhibitory. This power of imagination is best illustrated by the phenomena of hypnotic suggestion, paralysis of ideas, healing by faith, etc. These phenomena, however, do not, as is commonly supposed, consist merely in the intellectual production of mental images, but have at least three factors, an intellectual, an emotional, and an unconscious. The importance of the second of these is seen in the fact that not all can be healed by faith, but only those who are actuated by an impassioned desire, aversion, emotion, or passion. It is in the emotional factor, as purely organic, that the elixir vitæ is really to be found: it is the emotion that makes the image motor. The creative element, however, is to be found in all three factors. Considered from the point of view of the intellectual factor, imagination involves two complementary processes, 'association' and 'dissociation,' and from the mutual and constant interaction of these two processes no act of imagination can be purely reproductive, purely redintegrative, but is always to some extent creative: new elements are added, old ones omitted, according as the unique moral, emotional, and bodily condition of the subject dictates for the moment. The essence of creative imagination, therefore, on its intellectual side, is the faculty of "thinking by analogy," that is to say, by partial resemblance, and, as much, it lies at the basis of all creative or inventive genius, whether in art, literature, or practical life. If now we turn to the emotional factor, we find that it too can function creatively in the production of entirely novel intellectual combinations. States of consciousness may unite, not because of contiguity or resemblance, but because they have a common affective tone. Joy, sadness, love, hate, etc., may, therefore, become centers of attraction around which images group themselves which have no logical connection, and thus an almost unlimited field for intellectual invention is opened up for us. Nor must it be supposed that this emotional factor, is limited to the creative imagination of art and literature; it is also quite as prominent in mechanical invention, where it appears in diverse forms as joy, fear, hope, disappointment, satisfaction, etc.; no inventive act of thought is produced in abstracto, it is always tinged, and
