There is always an activity in inert matter that we little suspect. See the processes going on in the stratified rocks that suggest or parody those of life. See the particles of silica that are diffused through the limestone, hunting out each other and coming together in concretions and forming flint or chert nodules; or see them in the process of petrifaction slowly building up a tree of chalcedony or onyx in place of a tree of wood, repeating every cell, every knot, every worm-hole--dead matter copying exactly a form of living matter; or see the phenomenon of crystallization everywhere; see the solution of salt mimicking, as Tyndall says, the architecture of Egypt, building up miniature pyramids, terrace upon terrace, from base to apex, forming a series of steps like those up which the traveler in Egypt is dragged by his guides! We can fancy, if we like, these infinitesimal structures built by an invisible population which swarms among the constituent molecules, controlled and coerced by some invisible matter, says Tyndall. This might be called literature, or poetry, or religion, but it would not be science; science says that these salt pyramids are the result of the play of attraction and repulsion among the salt molecules themselves; that they are self-poised and self-quarried; it goes further than that and says that the quality we call saltness is the result of a certain definite arrangement of their ultimate atoms of matter; that the qualities of things as they affect our senses--hardness, softness, sweetness, bitterness--are the result of molecular motion and combination among the ultimate atoms. All these things seem on the threshold of life, waiting in the antechamber, as it were; to-morrow they will be life, or, as Tyndall says, "Incipient life, as it were, manifests itself throughout the whole of what is called inorganic nature." VIII The question of the nature and origin of life is a kind of perpetual motion question in biology. Life without antecedent life, so far as human experience goes, is an impossibility, and motion without previous motion, is equally impossible. Yet, while science shows us that this last is true among ponderable bodies where friction occurs, it is not true among the finer particles of matter, where friction does not exist. Here perpetual or spontaneous motion is the rule. The motions of the molecules of gases and liquids, and their vibrations in solids, are beyond the reach of our unaided senses, yet they are unceasing. By analogy we may infer that while living bodies, as we know them, do not and cannot originate spontaneously, yet the movement that we call life may and probably does take place spontaneously in the ultimate particles of matter. But can atomic energy be translated into the motion of ponderable bodies, or mass energy? In like manner can, or does, this potential life of the world of atoms and electrons give rise to organized living beings?