The sex-instinct, the last in chronological order with man and the higher animals, gives rise to the emotion of love with its numerous individual varieties. Most psychologists have been very sparing of details where it is concerned, and one might mention certain voluminous treatises which contain no mention of it. Is this through exaggerated delicacy? Or is it because the authors think that their place has been usurped by the novelists who have so obstinately confined themselves to the study of this passion? But the novelist’s mode of analysis is different from the psychological mode, and does not exclude it. Sexual love being an emotion whose evolution is complete, it is impossible to determine the physiological and psychical signs suiting all cases, from the blind instinct to the most refined and intellectualised forms. Nevertheless, there are certain specific characters which it always preserves, one special mark which is never effaced throughout its various metamorphoses, and that is, its origin. For the moment, let us take as typical the common and average forms which, as we shall see later on, are met with half-way, as we follow the evolution of sexual love from the lowest to the highest. 1. Though neither James nor Lange has cited it among his typical cases, love is certainly one of the emotions which express most clearly the state of the organism, and offer the clearest proof in favour of their theory. Let the reader suppress, in imagination, all the physiological manifestations which accompany it. What remains? not even the consciousness of a vague attraction, for that supposes an actual or nascent movement. Love, as a sthenic emotion, presents physical characteristics which connect it on the one hand with joy, on the other with tenderness, which have already been described. The circulation is accelerated, sometimes to an extreme degree, the respiration likewise, and they react on the organic functions. (We have already seen how, in many animals, the period of love corresponds to deeply-seated chemical modifications—usually of a toxic character—in the organism.) We find, further, movements of mutual repulsion, or of mutual attraction, the dominant part played by touch resumed in its essential organ, the hand, caresses, embraces, fusion; the movements of attraction being all the more noisy and violent, in proportion as the instinct predominates. Finally, as the specific mark, we find a particular state of the sexual organs, varying from slight excitement to paroxysm. This disturbance,—whether strong or weak,—even when it has no echo in the consciousness, influences the unconscious activity.[157] Footnote 157: