Mental functions are placed by Lancisi in close dependence on the nerves, the ganglia, and the coronary vessels of the heart. The material organs it is which influence mental movements. The heat of passion, the storm of emotions, have in the heart mechanisms by which they may be moderated and regulated. It is as though the nerves and ganglia of the heart, by driving the blood with more or less violence into the brain, could excite the instincts; as though the character and disposition of the mind depended on the material structure and the physical modifications of the body. CHAPTER VII _RESPIRATION AND OPPRESSION_ I Oppression on the chest has in it something so irresistible that the will cannot subdue it. A slight emotion, a little exertion, a loss of blood, or a fever is sufficient, nay, it is only necessary to enter a room where the air is warm or bad, to stoop or to go up steps, in order at once to accelerate the breath. So long as we are quiet, we may believe ourselves able to modify our respiratory movements at will; but, when the calm ceases, the working of our machine becomes apparent, and we are no longer able to arrest it. Our liberty is in no respect complete with regard to the functions of the organism. We are like children whom Nature allows to play so long as there is no danger to life. In order to understand the meaning of the continual variations which respiration undergoes, we must remember that our body is a very complicated furnace, in which, to keep the flame of life aglow, something must constantly be burnt. The respiratory movements, the expansion and contraction of the lungs, represent the untiring work of a bellows which keeps up the fire in the smithy of our organism. We may breathe in two ways: either we expand the upper part of the thorax by raising the ribs, or we expand it lower down by depressing the diaphragm. The first movement is more common with women, in whom the rise and fall of the bosom during emotion is so characteristic; the other is more usual with men. When we sleep it is especially the diaphragm which reposes; with some persons the abdomen is almost motionless during sleep, but a slight noise or push, a voice, or any external action suffices to make it resume its functions, and the diaphragmatic breathing becomes more active. This takes place suddenly, without our waking or being aware of it, and without any recollection of it remaining in consciousness.