In the history of the earth the chapter which precedes that written by the geologist is recited by the astronomer, whose keynote also is dynamic. The bulk, inclination, speed, and composition of the earth were all predetermined in the constitution, mass, and motion of the nebula which flung it forth. Dr. Huggins, his spectroscope before him, tells us that were the earth to resume a glowing heat it would yield much the same spectrum as the sun. Clearly, then, the scope of life on land and sea, the architecture of the forest, the ocean and the plain, with all their throbbing life, are what they are because the atoms which built them were present, and in such and such proportions, in the birth-cloud. If a blossom has tints of incomparable beauty, they are conferred by diverse elements thence derived, whose kin aflame in an orb, a celestial diameter away, send forth the beam needful to reveal that beauty. Were the sun less rich in variety of fuel than it is, the world, despite its own diversity of element, would be vastly less a feast for the eye than that which daily we enjoy.
As in the realm of organic life the modern interpretation is no longer static, so also in the sphere of Nature inorganic: it may be that all the thrust, recoil, and interaction in the life of plant and animal lay dormant in the simpler enginery of the atoms and molecules which build their frames and supply their food. It was one of the shrewd guesses of Sir Isaac Newton that the diamond is a combustible body; he did not suspect it to be one with coal in substance, but he observed it to be highly refrangible, as many combustible bodies are. His conjecture shows him to have taken the first step toward the view of modern physicists and chemists—namely, that properties, the modes of behavior of matter, are not passive qualities, but are due to very real activities; that what a substance is depends upon how in its ultimate parts it moves; just as organic structure can be deduced from living function because regarded as the creation of function, or, as in more familiar cases, the character of a die is inferred from its impress, and the construction of a machine read in the work it executes. Clausius and Maxwell, in a theory which marks an epoch, explained the elasticity of gases as manifesting the ceaseless motion of their molecules, declaring that an ounce of air within a fragile jar is able to sustain the pressure of the atmosphere around it, because the air, though only an ounce in weight, dashes against the containing walls with an impact forcible enough to balance the external pressure—proof whereof consists in measuring the velocity with which the air rushes into a vacuum. Here the significant point is that in leaving the realm of mass-mechanics, where the tax of friction is ever present and inexorable, we enter a sphere where motion of the swiftest can go on forever without paying friction the smallest levy. The elasticity of metallic springs has been