THE MECHANICS OF SOCIETY 239
the soul," of which Descartes treated, all loves and hates, fears and hopes, yearnings, longings, ambitions, aspirations, and a great variety of other forms of the one principle belong to it. 1 The central idea common to them all is embodied in the two words impulse and motive, and these terms sufficiently imply the indwelling force of the will. It is that which impels and that which moves. It is the nisits of nature transferred from the physical to the psychic world. It is force and motion ensouled. It is the true soul.
From the standpoint of social mechanics this embodiment of psychic and social energy becomes the dynamic agent. The word dynamic, primarily and etymologically relates to force, but usage has sanctioned its extension to include that which force normally accomplishes, viz., motion, change. In the expression "dynamic agent," both the narrower and the broader conceptions are involved, but in most of the other applications of the word "dynamic" it is mainly restricted to the narrower sense, and may be defined as : producing movement and change as the result of force. It is thus clearly distinguished in its scope from the term kinetic, employed in modern physics, which relates to motion only, without connoting force. The use of the term dynamics in the sense here indicated was first made in mechanics, and constitutes a department of that science in contradistinction to statics in which the forces are conceived as in equilibrium, so that no movement results. The next science in which a dynamic department was recognized was geology, and latterly the term is being applied to other sciences. From the principles with which we set out it is clear that every true science must have botli a dynamic and astatic department. This has been sparingly recognized in biology, and distinctly so in economics by Dr. Patten and in sociology by Comte.*
In treating of the mechanics of society, therefore, it is of the utmost importance to understand what constitutes social statics
1 Some attempt at an enumeration of these appetitive attributes may be found in The PiychU Factors of Civilization, pp. 53, 6l.
Not by Spencer, notwithstanding his work on "Social Statu
