2. The principle of antithesis has been definitively abandoned; it is purely hypothetical, and explains nothing. According to Darwin, there is a primitive and general tendency to associate with feelings the contrary gestures to those expressing the opposite feeling. Léon Dumont has subjected this assertion to a very close and cogent criticism. Taking, one by one, the facts quoted by Darwin, which, besides, are not very numerous, he has shown that they may be quite otherwise explained.[87] Footnote 87: L. Dumont, _Théorie scientifique de la sensibilité_, chap. vi. p. 236. Fouillée, _Psychologie des idées-forces_, i. 467, admits Darwin’s principle, but interprets it in another way. 3. The principle of the direct action of the nervous system cannot be placed in line with the other two, because it far surpasses them in generality, and, in relation to it, they are subordinate and not co-ordinate. Before Darwin, Spencer (_Principles of Psychology_, ii. §§ 495, 502) had stated an analogous principle, to which he reduced the expression of the emotions. He calls it the Law of Nervous Discharge. It may show itself in two forms—the diffused and the restricted. The former depends on the quantity or intensity of the emotion, and serves as its measure. It follows, in its propagation, an invariable course: it affects the muscles in an inverse ratio to their mass and to the weight of the parts they have to move. In man, it acts first on the delicate muscles of the voice and the small facial muscles; then it invades, in succession, the arms, the legs, the trunk. The movements of the tail in dogs and cats, of the ear in horses, and many analogous ones in other animals, are illustrations of this law. The restricted discharge depends on the quality or the nature of the emotion; it is due “to the relations established in the course of evolution between particular feelings and particular sets of muscles habitually brought into play for the satisfaction of them.”[88] This scarcely seems to me to differ from Darwin’s principle of “useful habits.” Footnote 88: _Principles of Psychology_, vol. ii. p. 545. The _Expression of the Emotions_ gave rise to other publications of the same kind, those of Piderit, Mantegazza, and Warner, who, in his _Physical Expression_ (1885), has attempted a purely objective, and consequently extra-psychological study of the subject. But among all the attempts to trace back expression to its fundamental principles, and find a substitute for Darwin’s (already greatly shaken) theory, that of Wundt seems to me the best.[89] Like his predecessor, he admits three principles (though different from Darwin’s) which can act simultaneously and concur in the production of an isolated movement. Footnote 89: _Physiologische Psychologie_, vol. ii. chap. xxii. He has also treated the question in a special collection of articles entitled _Essays_.