IV. This universal movement of substance in space takes the form of an eternal cycle or of a periodical process of evolution. V. The phases of this evolution consist in a periodic change of consistency, of which the first outcome is the primary division into mass and ether--the ergonomy of ponderable and imponderable matter. VI. This division is effected by a progressive condensation of matter as the formation of countless infinitesimal "centres of condensation," in which the inherent primitive properties of substance--feeling and inclination--are the active causes. VII. While minute and then larger bodies are being formed by this pyknotic process in one part of space, and the intermediate ether increases its strain, the opposite process--the destruction of cosmic bodies by collision--is taking place in another quarter. VIII. The immense quantity of heat which is generated in this mechanical process of the collision of swiftly moving bodies represents the new kinetic energy which effects the movement of the resultant nebulæ and the construction of new rotating bodies. The eternal drama begins afresh. Even our mother earth, which was formed of part of the gyrating solar system millions of ages ago, will grow cold and lifeless after the lapse of further millions, and, gradually narrowing its orbit, will fall eventually into the sun. It seems to me that these modern discoveries as to the periodic decay and re-birth of cosmic bodies, which we owe to the most recent advance of physics and astronomy, associated with the law of substance, are especially important in giving us a clear insight into the universal cosmic process of evolution. In their light our earth shrinks into the slender proportions of a "mote in the sunbeam," of which unnumbered millions chase each other through the vast depths of space. Our own "human nature," which exalted itself into an image of God in its anthropistic illusion, sinks to the level of a placental mammal, which has no more value for the universe at large than the ant, the fly of a summer's day, the microscopic infusorium, or the smallest bacillus. Humanity is but a transitory phase of the evolution of an eternal substance, a particular phenomenal form of matter and energy, the true proportion of which we soon perceive when we set it on the background of infinite space and eternal time.