(_b_) Force implies a will of which it is the direct or indirect expression. We know of force only through the exercise of our own wills. Since will is the only cause of which we have direct knowledge, second causes in nature may be regarded as only secondary, regular, and automatic workings of the great first Cause. For modern theories identifying force with divine will, see Herschel, Popular Lectures on Scientific Subjects, 460; Murphy, Scientific Bases, 13-15, 29-36, 42-52; Duke of Argyll, Reign of Law, 121-127; Wallace, Natural Selection, 363-371; Bowen, Metaphysics and Ethics, 146-162; Martineau, Essays, 1:63, 265, and Study, 1:244—“Second causes in nature bear the same relation to the First Cause as the automatic movement of the muscles in walking bears to the first decision of the will that initiated the walk.” It is often objected that we cannot thus identify force with will, because in many cases the effort of our will is fruitless for the reason that nervous and muscular force is lacking. But this proves only that force cannot be identified with human will, not that it cannot be identified with the divine will. To the divine will no force is lacking; in God will and force are one. We therefore adopt the view of Maine de Biran, that causation pertains only to spirit. Porter, Human Intellect, 582-588, objects to this view as follows: “This implies, first, that the conception of a material cause is self-contradictory. But the mind recognizes in itself spiritual energies that are not voluntary; because we derive our notion of cause from will, it does not follow that the causal relation always involves will; it would follow that the universe, so far as it is not intelligent, is impossible. It implies, secondly, that there is but one agent in the universe, and that the phenomena of matter and mind are but manifestations of one single force—the Creator’s.” We reply to this reasoning by asserting that no dead thing can act, and that what we call involuntary spiritual energies are really unconscious or unremembered activities of the will.