THE MECHANICS OF SOCIETY 237
row. It embraces only the thinking faculty, or at most, that and the special senses. Now, suppose we try to define the sev- eral great groups of phenomena that are constantly appealing to us in the ascending order of their complexity, beginning with that of gravitation and rising through the radiant group of heat, light, electricity, etc., and the group of elective chemical affin- ities, to the vital group, including everything that relates to life but does not relate to mind ; and then pass directly to the senses and the intellect. A glance is sufficient to show that a great group has been omitted. This lies between the vital group and the intellectual group. It constitutes the entire domain of feel- ing. This domain is distinct from the senses in the popular usage, for these do not necessarily involve conscious feeling at all. Those of sight and hearing are feelingless, and even that of touch, sometimes called the sense of feeling, need not involve feeling, and its value as a sense, i. e., as a means of furnishing the mind with a knowledge of the nature of the objects touched, is inversely proportional to the amount of feeling. I call this indifferent sensation in contradistinction to feeling proper, which I call intensive sensation. This latter is always either pleasure or pain of whatever degree, and it would be easy to show that it is the primary form of feeling, and that the indifferent form is secondary and of far later origin. In fact intensive sensation pleasure and pain constitutes the simplest and earliest manifestation of the psychic faculty. This great field of phenomena the domain of feeling is not physical, chemical, or vital ; it must therefore be psychic and belong to mind.
We thus arrive at the dual nature of mind. It has a great primary department of feeling and an equally great but second- ary department of thought. The former I have called the affective side of mind ; the latter its perceptive side. The affective department of mind has formed no part of the philosophy of mind. It has only been seriously treated under the head of moral philosophy, and thus chiefly for the purpose of warning against the power of the passions. It has been regarded as
