principles. Helmholtz, in his latest writings, fully adopts this doctrine of corporeal extension.
We thus see that there is no difficulty in reconciling extension with unextended forces, and the phenomena of extension with principles of action; but this is only the first part of the problem, and it becomes necessary now to ascend from these unextended forces and active principles to those more or less complex manifestations which make up the infinite universe, adorning space with imperishable variety. Let us imagine this universe filled with the greatest conceivable number of active principles, all identical, diffused uniformly throughout immensity, and consequently in a state of perfect equilibrium. All will be torpid in absolute repose, in which form without shape and force without spring will be as though they were not. Between a homogeneous, motionless substance, identical with itself throughout space at all points, and nihility, reason perceives no difference. In such a system, nothing has weight, for there is no attracting centre; heat is no more possible for it than light, since these two forms of energy are bound up with the existence of systems of unequal vibrations, of diversified media, and varying molecular arrangements. A fortiori, the phenomena of life will be incompatible with this universal unity of substance, this unchanging identity of force.
The objective existence of things, the coming into reality of phenomena, can only be conceived, therefore, as the work of a certain number of differentiations taking place in the deep of that universal energy of primal matter, which is the last result of our analysis of the world. Motion, of itself alone, is enough to explain a first attribute of that energy, namely, resistance, and its consequence, impenetrability; but this is only on the condition that this motion shall take place in various directions. Two forces urged in opposite directions, and coming to a meeting, manifestly resist each other. It is probably by collisions of this sort that those variable condensations of matter, and those heterogeneous groupings of which the world presents the spectacle, have been determined. A rotary movement, communicated to a mass without weight, can only engender concentric spheres, which gravitate toward each other in consequence of pressure by the interposing ether. The famous experiments of Plateau are decisive in this respect. That accomplished physicist introduces oil into a mixture of water and alcohol, having exactly equal density with the oil itself. He inserts a metallic strip into the midst of this mass of oil, which is free from the action of any force, and turns it about. The oil takes the form of a sphere, and, as soon as the rotation grows very rapid, breaks up, and parts into a number of smaller spheres. The celestial spheres were probably formed in the same way, and an exactly similar mechanical action produces those clear dew-drops, glittering like diamonds, on the leaves of plants.
All physical phenomena, whatever their nature, are at bottom only
