There are unusual and remarkable cases with an exceptional emotional base. Of such is "colored hearing." We know that several hypotheses have been offered in regard to the origin of this phenomenon. Embryologically, it would seem to be the result of an incomplete separation between the sense of sight and that of hearing, and the survival, it is said, from a distant period of humanity, when this state must have been the rule; anatomically, the result of supposed anastamoses between the cerebral centers for visual and auditory sensations; physiologically, the result of nervous irradiation; psychologically, the result of association. This latter hypothesis seems to account for the greater number of instances, if not for all; but, as Flournoy has observed, it is a matter of "affective" imagination. Two sensations absolutely unlike (for instance, the color blue and the sound _i_) may resemble one another through the equal retentive quality that they possess in the organism of some favored individuals, and this emotional factor becomes a bond of association. Observe that this hypothesis explains also the much more unusual cases of "colored" smell, taste, and pain; that is, an abnormal association between given colors and tastes, smells, or pains.
Although we meet them only as exceptional cases, these modes of association are susceptible to analysis, and seem clear, almost self-evident, if we compare them with other, subtle, refined, barely perceptible cases, the origin of which is a subject for supposition, for guessing rather than for clear comprehension. It is, moreover, a sort of imagination belonging to very few people: certain artists and some eccentric or unbalanced minds, scarcely ever found outside the esthetic or practical life. I wish to speak of the forms of invention that permit only fantastic conceptions, of a strangeness pushed to the extreme (Hoffman, Poe, Baudelaire, Goya, Wiertz, etc.), or surprising, extraordinary thoughts, known of no other men (the symbolists and decadents that flourish at the present time in various countries of Europe and America, who believe, rightly or wrongly, that they are preparing the esthetics of the future). It must be here admitted that there exists an altogether special manner of _feeling_, dependent on temperament at first, which many cultivate and refine as though it were a precious rarity. There lies the true source of their invention. Doubtless, to assert this pertinently, it would be necessary to establish the direct relations between their physical and psychical constitution and that of their work; to note even the particular states at the moment of the creative act. To me at least, it seems evident that the novelty, the strangeness of combinations, through its deep subjective character, indicates an emotional rather than an intellectual origin. Let us merely add that these abnormal manifestations of the creative imagination belong to the province of pathology rather than to that of psychology.