Now, to give motion or to resist motion is itself either a breach or a use of a law of Nature, according as we express that law. The law is (as usually expressed), that matter at rest remains at rest till moved by a force, and that matter in motion continues in motion till stayed by a force. This is the law of inertia. If we consider that rest or motion when once established is the normal state of matter, then the force which causes a change causes a breach of the law of inertia. But if we consider that the liability to be moved, or to have motion stopped by force, is itself a property of matter, then the application of force with such result is merely calling into operation the law of inertia. It really does not signify which view we take, so long as we recognize that such are the facts. But since it is more familiar to associate rest with inertia, it will perhaps be most convenient and simple to consider rest and motion as the laws of matter, till the law is interfered with. Therefore in what follows we shall say, that when matter at rest is moved, or when matter in motion is stayed, or its movement by a natural force is prevented, a breach of the law of inertia is committed.
We come, then, to these propositions:--1st, That human power is utterly unable to break any law of matter except the law of inertia. 2nd, That when, by breaking only the law of inertia--_i.e._, by moving or by resisting the motion of matter--any operation is accomplished, no other law of matter is broken. 3rd, That to break the law of inertia by Force, directed by Will, is no interference with the properties of matter. 4th, That by breaking the law of inertia only, man has power to call into play properties which make matter subservient to his objects.
Nor is this man's power only. Inferior animals can also move matter, and by moving it can cause prodigious results. A minute insect, by secreting lime from sea waters, makes a coral reef, or aids in forming a cliff of chalk. A beaver cuts down a tree, and forms a swamp that changes the climate of a district; a bird carries a seed, and makes a forest on an island. Inanimate life has the same power. The plant opens its leaves to the sun, and abstracts the carbon that forms fruitful soils and beds of coal. Matter itself can by motion work on matter. The great physical powers, heat and electricity, are modes of motion. Radiation of heat causes freezing, and freezing crumbles rocks into soil, or it forms the clouds in the air, whose deluges hollow valleys; while electricity cleaves and splinters the summits of the mountain peaks. Everywhere motion, sharp or slow, works with matter; everywhere the law of inertia is broken; and everywhere the miracles of Nature are wrought out by Nature's unbroken laws, set in action or withheld by only the movement which matter has received, be it from Will in man or beast, or be it from forces which themselves are part of matter's properties.