1. The brain is not merely the echo of internal sensations; it receives and reacts according to its disposition; it centralises, but while taking its own part in the concert; it puts its mark on the impressions it receives. Already (Chap. I., § 1) we have seen the theories propounded as to the “seat” or “centre” of pain or pleasure: bulb, protuberance, temporal lobe, occipital lobe, etc. Naturally, each author has extended his hypothesis to the emotions properly so called. However, the search for “emotional centres” appears still more chimerical. A particular emotion has no determinate centre, is not localised in a restricted area of the encephalon. Not only does neither observation nor experience indicate anything of the sort, but if we consider the complexity of any emotion whatever, we shall understand that it requires the activity of several cerebral and infra-cerebral centres: (1) the sensory centres of sight, hearing, smell, etc.; (2) the centres scattered through the motor zone and regulating the movements of different parts of the body; (3) and lastly, the centres corresponding to the phenomena of organic life. These constitute several stages: in the spinal cord, the respiratory centre, that which accelerates the movements of the heart, the genito-spinal, the vesico-spinal (it is well known that the bladder is as good an æsthesiometer as the iris), etc.; in the bulb, the respiratory and vaso-motor centres, and those of cardiac and thermic inhibition. As regards the cortical layer, there are many open questions as to the position of the vascular, thermic, trophic, glandular centres, of the organic movements which determine the contraction of the intestines, the bladder, the spleen, etc. This very incomplete and confused enumeration is sufficient for our purpose—viz., to show that we must speak, not of a centre, but of the synergic action of several centres, differently grouped according to the cases.[80] Footnote 80: In his lectures on Hysteria (Vol. i., Lecture 21), Pitres incidentally inquires into the existence of encephalic centres of the affective states, and concludes that “the molecular changes corresponding to the activity of the cellular elements shaken by the passions, radiate in every direction, stimulate or depress the excitability of adjacent elements, rebound on the motor and sensitive centres, and on the originatory nuclei of the visceral nerves, and finally determine the state of emotion, _i.e._, the psycho-physiological state which is the special expression of the reaction of the nervous centres to psychic excitations.”