The molecule of matter such as we know, then, may have been, and very probably was, produced by evolution from the atoms or vortex rings of ether, according to the theory advanced by the authors of the work called the "Unseen Universe," which I have referred to. The world of ether is to be regarded in some sort the obverse complement of the world of sensible matter, so that whatever energy is dissipated in the one is by the same act accumulated in the other; or, as Fiske describes it, "it is like the negative plate in photography, where light answers to shadow and shadow to light." Every act of consciousness is accompanied by molecular displacements in the brain, and these of course are responded to by movements in the ethereal world. Views of this kind were long ago entertained by Babbage, and they have since recommended themselves to other men of science, and amongst others to Jevon, who says: "Mr. Babbage has pointed out that if we had power to follow and detect the manifest effects of any disturbance, each particle of existing matter must be a register of all that has happened. * * * The air itself is one vast library on whose pages are forever written all that man has ever said or whispered. There in their mutable but unerring characters, mixed with, the earliest as well as the latest sighs of mortality, stand forever recorded vows unredeemed, promises unfulfilled, perpetuating in the united movements of each particle the testimony of man's changeful will."[83] So thought affects the substance of the present visible universe; it produces a material organ of memory. "But the motions which accompany thought," say the authors,[84] "will also affect the invisible order of things," and thus it follows that "thought conceived to affect the matter of another universe, simultaneously with this, may explain a future state."[85]