Psychologically, it is a construction in images belonging to the merely sketched or outlined type.[30] It results from a double activity, negative and positive, or dissociation and association, the first cause and origin of which is found in a _will that it shall be so_; it is the motor tendency of images in the nascent state engendering the ideal. The inventor cuts out, suppresses, sifts, according to his temperament, character, taste, prejudices, sympathies and antipathies--in short, his _interest_. In this separation, already studied, let us note one important particular. "We know nothing of the complex psychic production that may simply be the sum of component elements and in which they would remain with their own characters, with no modification. The nature of the components disappears in order to give birth to a novel phenomenon that has its own and particular features. The construction of the ideal is not a mere grouping of past experiences; in its totality it has its own individual characteristics, among which we no more see the composing lines than we see the components, oxygen and hydrogen, in water. In no scientific or artistic production, says Wundt, does the whole appear as made up of its parts, like a mosaic."[31] In other words, it is a case of mental chemistry. The exactness of this expression, which is due, I believe, to J. Stuart Mill, has been questioned. Still it answers to positive facts; for example, in perception, to the phenomena of contrast and their analogues; juxtaposition or rapid succession of two different colors, two different sounds, of tactile, olfactory, gustatory impressions different in quality, produces a particular state of consciousness, similar to a combination. Harmony or discord does not, indeed, exist in each separate sound, but only in the relations and sequence of sounds--it is a _tertium quid_. We have heretofore, in the discussion of association of ideas, very frequently represented the states of consciousness as fixed elements that approach one another, cohere, separate, come together anew, but always unalterable, like atoms. It is not so at all. Consciousness, says Titchener, resembles a fresco in which the transition between colors is made through all kinds of intermediate stages of light and shade.... The idea of a pen or of an inkwell is not a stable thing clearly pictured like the pen or inkwell itself. More than any one else, William James has insisted on this point in his theory of "fringes" of states of consciousness. Outside of the given instances we could find many others among the various manifestations of the mental life. It is not, then, at all chimerical to assume in psychology an equivalent of chemical combination. In a complex state there is, in addition to the component elements, the result of their reciprocal influences, of their varying relations. Too often we forget this resultant.