with a system of nerves connected with the great nerve-center. If a disturbance arises in one of the viscera, some action that is abnormal, a sensation that is called pain is produced. So, too, in regard to the normal action of the viscera, kept up by involuntary movements--those movements originate in and are transmitted from the nerve-center, by waves in the fluid or semi-fluid substance of which the special nerves are composed, whose office it is to cause the necessary movements in the muscular substance, or the tissue, of the particular organ. In this way began, in the supposed individual, those simpler states of feeling which pain or irritation produced in the nervous system, and those other involuntary movements which were essential to the normal and unconscious action of the viscera. These varying conditions of the highly sensitive nervous system, which constitute and are rightly denominated feelings, were constantly repeated; and, so far as they are capable of becoming a part of consciousness, that consciousness is a repetition of the same nervous actions many times over. Pass, then, from the feelings called sensations to the feelings called emotions, and it will be found that while both are states of nervous action, the former are peripherally initiated and the latter are centrally initiated. The meaning of this is that a sensation is an effect produced at the nerve-center by the transmission, from the outer terminus of a particular nerve, of the waves in the fluid or semi-fluid substance of the nerve. The strong forms of feeling called sensations are peripherally initiated, and the feelings called emotions are centrally initiated. Now, any feeling of any kind is directly known by each person in no other place than his own consciousness; and the question is, Of what is consciousness composed? In order to afford an answer to this question, Mr. Spencer proceeds to examine the substance of mind, and then passes to a consideration of the composition of mind. These are not the same thing; for, if there be no such thing, properly speaking, as the substance of mind, its composition, or its nature, must be looked for in another way. The expression "substance of mind," if used in any way but that in which we use the _x_ of an algebraic equation, has no meaning. If we undertake to interpret mind in the terms of matter, as crude materialism does, we are at once brought to this result, that we know, and can know, nothing of the ultimate substance of either. We know matter only as forms of certain units; but the ultimate unit, of which the ultimate homogeneous units are probably composed, must remain absolutely unknown. In like manner, if mind consists of homogeneous units of feeling, the ultimate unit, as a substance, must remain unknown. When, therefore, we think of the substance of mind, the simplest form under which we can think of it is nothing but a symbol of something that can never be rendered into