There is no rest in the world of Substance. Everything is changing--constantly changing. Old forms give way to new, and these, grown old while being born, are, in turn replaced by still newer. And on, endlessly. Nothing persists but change. And yet nothing is destroyed, although countless forms and shapes have succeeded each other. Substance is always there, undisturbed and unaffected by the varieties of forms it is compelled to undergo. Masses may change--and do change. Molecules may change--and do change. Disintegration and decomposition affect both, and bring to them the death of form. But their substance endures in the Atom. Atoms may change, and decompose, or undergo whatever change that is their fate, and still the Corpuscles, or what lies beyond the Corpuscles will remain. The Atom was once regarded as Eternal, but now even it seems to be capable of dissolving into some finer division of Substance--and perhaps still finer subdivisions await it. That familiar form of Substance that we call "earth," "dirt," "soil," etc., is but the result of disintegrated rock, which has crumbled and lost its former form through the action of air, water and atmospheric influences. And the rocks themselves, from which the "soil" came, were at one time a sea of melted, flowing liquid Substance, somewhat resembling volcanic lava. And this "melted rock" is thought to have been condensed from the same principles in the shape of vapor, that existed in the early days of our planetary system. Vapor, gas, liquid, semi-liquid, solid rock, "soil"--the Substance unchanged, the forms totally unlike. Helmholtz estimates the density of the nebulous vapors of Substance as being so rare that it would take several millions of cubic miles of it to weigh a single grain. Oh, Nature, what a wizard thou art!