It is true that Polarity is called in to assist the endeavour, but it is a polarity which is the obedient servant of the author, and does as it is bid, firstly in being so amenable to changed conditions as to alter conformably with them, and again in being so rigid in its acquired form as to coerce molecules into definite construction. It is alternately so pliable and so fixed as, hand over hand, to enable the author to scale the highest summits of Biology. It is also true that Equilibration is called in: but then every change in the organic and the inorganic world turns out to be an equilibration, so that the word becomes devoid of meaning. A more special study has to be given to Mr. Spencer's theory of the moving equilibrium with which he identifies the existence of an organism, and by means of which he is supposed to bridge over the chasm between it and the inorganic. The idea is derived from a consideration of the spinning top, the solar system, and the steam engine, more particularly if the latter is self-feeding! These are moving equilibria, and if their motions are disturbed by some external object they will generate forces in opposition to the environment. This purely mechanical conception is then rendered into an abstract form by the substitution of the idea of related _forces_, as constituting a moving equilibrium, and is found to fit the abstract conception of an organism, so that the solar system and the organism can both be identified as moving equilibria. Next, by loosely characterising the behaviour of the solar system in its relation to its environment, real or hypothetical, as consisting of changes due to the laws of a moving equilibrium, Mr. Spencer seeks to show that the adaptations of an organism in response to changed external conditions are likewise due to the same laws, so that organisms and their histories are supposed to be explainable or accounted for both in their origin and in their development in the same manner as the moving equilibria of the physical world. Thereupon we are supposed to understand both why organisms generate forces to counterbalance inimical external forces, and why they generate forces (adaptations) for securing and absorbing forces of the environment (food) favourable to their continued existence. It is only what all moving equilibria do. This biological theory we have discussed at great length elsewhere,[5] and we then came to the conclusion that it was only a mockery of a rational explanation. We also found that the facts of Genesis and the Law of Heredity were wholly inexplicable by means of a study of physics or by means of a study of the nature and laws of the moving equilibrium. So that altogether we found the main requirements of a philosophical explanation of biological facts very far from being complied with.