The place to be assigned to Purpose in a process of equilibration is not very clear. In the first place, if the biological explanations are all strictly limited to the chemical and physical factors, it seems evident that there can be no purposive actions, since all actions are determined by the chemical and mechanical relations of molecules, masses of molecules, and organised masses of molecules. To say that what we call purposive actions are explicable by physical and mechanical laws is to abolish purpose and substitute physical causation. Can purpose by any means be made lineable in such a sequence? The problem is a fair one to consider and to attempt. We fail to do it, and we think that all who have attempted it have failed. But if a subjective factor is admitted into the problem, then it is necessary to understand in what way it becomes part of, and in what way it affects, a process of equilibration on the part of a moving equilibrium in which it is a factor. The peculiar nature of a biological moving equilibrium, and the respect in which it differs from a physical or mechanical moving equilibrium, consists in the fact that it works towards, if indeed it does not purposely aim at self-continuance by assimilation of force and self-continuance by means of self-protection from adverse forces in the environment. The coincidence of the subjective element with this tendency, in many equilibria, is suggestive of an efficient connexion. Yet if we do not understand the law of the relation of a subjective factor with the physical and mechanical factors, how can we understand the resultant process of equilibration and the necessity for the biological law of adaptations for self-preservation and self-protection? How can we understand Purpose as an equilibration? Ethics to be affiliated upon the cosmical process requires that we should understand how purposive actions can be so affiliated, for Ethics relates to purposive actions. In the failure of such a logical connexion, we may understand Ethics on partial and limited grounds, but we do not understand it as Mr. Spencer proposes we should understand it, namely, as part of the cosmical process.