This kind of classification, in the first place, establishes two great categories of emotions—those depending on the _contents_ of the representations, and those depending on the _course_ of the representations. Let us compare the flux of the states of consciousness to that of a river, which, according to the nature of the soil and the state of the sky, runs, sometimes clear, sometimes muddy, sometimes blue or green, sometimes greyish. Besides these various aspects, there is yet another kind, depending on the movement of the water, sometimes slow, sometimes rapid, here stagnant, there broken by the abrupt windings of the banks. One of these corresponds to the course, the other to the contents of the representations on which the affective states are based. The first class (the contents) comprises the qualitative emotions, which are generally divided into inferior or sensory, and superior, which are intellectual, æsthetic, moral, or religious, according as the ideas exciting their feelings are those of the true, the beautiful, the good, or the absolute. The second class (the course of the representations) comprises the _formal_ emotions—_i.e._, those depending on the different forms of the course of ideas, on the relations existing between them. Nahlowsky distinguishes four species—(1) the feeling of expectation and impatience; (2) that of hope, anxiety, surprise, doubt; (3) of _ennui_; (4) of refreshment and work. The only merit of this classification is its showing that there are affective manifestations depending only on relations—transitions from one intellectual state to another. This merit, however, depends on the essential defect of the system, which consists in dealing with perceptions, representations, and ideas only—not with affective states taken in themselves, and directly. As this method of procedure is, definitively, an intellectual classification, it ought not to omit any form of knowledge, not even those blurred and evanescent states—the relations—which unite, disjoin, exclude, draw together, eliminate, subordinate, in short, indicate the _movements_ of thought, and which students have often made the mistake of forgetting. It remains to be known whether many relations are not states of an affective rather than an intellectual nature; this is a point which I shall examine later on. We may console ourselves for this multiplicity and divergence of classifications by saying that the naturalists have not been more successful. It will be granted without difficulty that it is easier to classify animals than affective states; yet, to take our own century only, how many systems!—from Lamarck, Cuvier, Oken, to Blanville, Geoffroy St. Hilaire, Siebold, Ehrenberg, Richard Owen, Von Baer, Vogt, Agassiz, and finally to Häckel—if we cite only the principal names!