Duchenne has the following curious passage:—"The Creator, not being obliged to study mechanical requirements, was able, according to His wisdom or (if I may be pardoned for using this form of expression) by a Divine fantasy, to put in action this or that muscle—a single one, or several at once, when it was His will that the signs of the passions, even the most evanescent, should be temporarily inscribed on the human countenance. This physiognomic language once created, it was sufficient, in order to render it universal and immutable, to give to every human being the instinctive faculty of always expressing his feelings by the contraction of the same muscles." Thus, for this writer, the question remains within the region of first causes. He has ascertained a relation of coexistence between a determinate emotion and certain movements of the muscles, but without seeking the reason and the natural explanation of this _nexus_. We know that certain philosophers hold the theory of the Divine institution of language; this is its equivalent, being a theory of a divinely instituted gesture-language. In Darwin’s works we find two elements: a detailed and complete description of each individual emotion or affective state—by which we shall profit later on—and the exposition of the general laws of expression, as reduced to three well-known principles. What remains of these three principles after the criticism to which they have been subjected? This is the only point we have, for the moment, to examine. 1. The principle of the association of serviceable habits remains the most firmly established. It consists in admitting that movements which are of service in satisfying a desire, or getting rid of a disagreeable sensation, become habitual, and continue to take place, even when their utility becomes _nil_, or at any rate doubtful. In other words, there are attitudes, gestures, movements, which can be directly explained, because they are nothing but emotions actualised, objectivised, or embodied, such as the movements of contact in tenderness, of aggression in anger, of erection and swelling in pride. But there are others, of which the explanation is less direct and obvious. How are the contraction of the eyebrows in perplexity, tears in sorrow, the showing of the teeth in anger, to be explained as serviceable to us? According to Darwin, these acts, formerly serviceable, have continued to exist as survivals. Here Darwin’s successors have rightly reproached him with not being enough of a psychologist, and have found a better explanation: the important fact is not the survival of serviceable movements, but the transference of a primitive mode of expression to an analogous emotion.