It is preferable to begin with the feeling-tones of definitely physical origin, because these hedonic elements have been subjected to an experimental investigation which could never be undertaken with regard to the complex emotions and sentiments. As early as 1887 Féré published some important researches on the relation between sensation and movement. By submitting persons to various external stimuli, he showed that every such stimulus calls forth a modification of the activities of the body, which modification, according to the intensity and the duration of the stimulus, takes the character either of enhancement or of arrest. In all cases when the apparatus used in the experiments indicated a shortened reaction-time and an increased development of energy, the subject of the experiment had experienced a feeling of pleasure. Every painful stimulus, on the other hand, was connected with a diminution of energy.[41] These results have been corroborated in the main by the later researches of Lehmann. He has not, however, restricted his attention to the development of energy, but has also measured the changes in pulsation and respiration which occur under the influence of various stimuli. His conclusions are these:— “Simple pleasurable sensations are accompanied by dilatation of the blood-vessels, and perhaps also by an increase in the amplitude of heart-contraction, together with an increase in the innervation of the voluntary muscles, at least of those connected with respiration. In sensations of pain one has to distinguish the first shock of irritation from the subsequent state. At the moment of irritation there ensues a deeper inhalation, and, if the irritation is strong, also an increase in the innervation of voluntary muscles. Then there generally follows a relaxation.”[42] The physiological theory of pleasure and pain which can be deduced from these experiments is, however, neither new nor original. Féré has himself pointed out that his researches only serve to prove the views which have been advanced with more or less explicitness by Kant, Bain, Darwin, and Dumont.[43] All authors who have closely studied the movements of expression have also remarked that pleasurable feelings are accompanied by a tendency towards increased activity (Gratiolet, Darwin, Bain, Bouillier, Mantegazza).[44] And the popular views on pleasure and pain, as we find them expressed in literature, all agree on this point: “La joie est l’air vital de notre âme. La tristesse est un asthme compliqué d’atonie.”[45] Every one knows that movement and unchecked increased activity generally create pleasure. And, on the other hand, functional inhibition is in our experience closely connected with feelings of pain.