And just as a particular arrangement, for instance, of zinc and carbon and sulphuric acid, leads to the evolution of galvanism, so a particular arrangement of nerve-cells leads to the evolution of the force that we call mind. We can not explain why or how the galvanism comes from the zinc, carbon, and sulphuric acid; neither can we tell why or how mind comes from the nerve-cells. Both are ultimate facts beyond which we can not go, and may never be enabled to go.
Now, as by their properties we recognize any of the other forces of Nature that I have mentioned, so by its properties we recognize mind. An object is perceived, and it is the mind that perceives it; an idea is formed, and it is the mind that forms it; an emotion is felt, and it is the mind that feels it; an act is willed, and it is the mind that wills it. Hence, there are these four groups of mental faculties, to one of which every possible manifestation of mind belongs—perception, intellect, emotion, and will.
The many interesting points concerned with these categories of mental faculties do not come within the scope of the present remarks, the chief object of which is to discuss the subject of the relations existing between the mind and the nervous system.
In the very earliest times of which we have any record, and even at the present day among barbarous nations, the idea existed that the brain was not the only organ concerned in the production of mind. Thus, the emotions were, many of them, supposed to have their seat in the heart, the liver, the spleen, the bowels. Love, for instance, was conceived by the heart, as were also several other tender or compassionate feelings. The liver was supposed to be intimately connected with the depressing emotions, the spleen with spite or revenge, and the bowels with pity. So strongly was this idea implanted, and so universally did it prevail, that it has influenced the forms of speech among all nations that are not so low in the scale as not to have emotions. Thus we say that a person has "a good heart," the lover tells his lady-love that he "loves her with all his heart," and the sinner when he turns away from his wickedness is said to have undergone a "change of heart." The influence ascribed to the liver is shown by our expressions "melancholic," "choleric," and by one that I heard used a short time since by a man who was complaining of an insult that had been put upon him, and who said that it made "his bile flow." Then we say of a disagreeable or quarrelsome person that he is "splenetic," or that he "vents his spleen," and we speak of a pitiless person by asserting that he has "no bowels of compassion."
How could the notions that gave birth to such expressions arise in the human mind? Doubtless, the origin was due to the fact that, under the influence of certain emotions, there are disturbances in the organs with which they are associated. Thus, the passion of love produces a sensation of fullness in the region of the heart, and the action of the organ is quickened. In mental depression, or as a consequence