5. Idealism has been the outcome of the psychological method. It has been of immense service in rectifying the dualistic conception, and in correcting the mechanical conception. It has restored the subjective factor, which the mechanical conception had eliminated. It has brought into incomparable clearness the fundamental fact that all our knowledge _springs from_, and is _limited by_, Feeling. It has shown that the universe represented in that knowledge, can only be a picture of the system of things as these exist in relation to our Sensibility. But equally with the mechanical conception it has erred by incomplete analysis. For a complete theory of the universe, or of any one phenomenon, those elementary conditions which analysis has provisionally set aside must finally be restored. When Quality is replaced by Quantity, this is an artifice of method, which does not really correspond with fact. The quality is the fact given in feeling, which we analytically refer to quantitative differences, but which can never be wholly resolved into them, since it must be presupposed throughout. One color, for example, may be distinguished from another as having more or fewer undulations; and so we may by abstraction, letting drop all qualitative characters, make a scale of undulations to represent the scale of colors. But this is an ideal figment. It is the representation of one series of feelings by another series of different feelings. No variation of undulations will really correspond with variation in color, unless we reintroduce the suppressed _quality_ which runs through all color. Attempt to make one born blind feel, or even understand, Color by describing to him the kind of wave-movement which it is said to be, and the vanity of the effort will be manifest. Movement he knows, and varieties of movement as given in _tactile and muscular sensations_; but no combination and manipulation of such experiences can give him the specific sensation of Color. That is a purely subjective state, which he is incapable of experiencing, simply because one of the essential factors is absent. One set of objective conditions is present, but the other set (his sense-organ) is defective. Without the “greeting of the spirit” undulations cannot become colors (nor even undulations, for these also are forms of feeling). Besides the sense-organ there is needed the feeling of Difference, which is itself the product of past and present feelings. The reproduction of other colors, or other shades of color, is necessary to this perception of difference; and this involves the element of Likeness and Unlikeness between what is produced and reproduced. So that a certain mental co-operation is requisite even for the simplest perception of quality. In fact, psychological analysis shows that even Motion and Quantity, the two objective terms to which subjective Quality is reduced, are themselves Fundamental Signatures of Feeling;[205] so that here, as elsewhere, it is only by analytical