194. Now, if we regard the dissipation of energy which is constantly going on, we are at first sight forcibly struck with the apparently wasteful character of the arrangements of the visible universe. All but a very small portion of the sun’s heat goes day by day into what we call empty space, and it is only this very small remainder which can be made use of by the various planets for purposes of their own. Could anything be more perplexing than this seemingly prodigal expenditure of the very life and essence of our system? That all but a petty fraction of this vast store of high-class energy should be doing nothing but travelling outwards in space at the rate of 188,000 miles per second is hardly conceivable, especially when the result of it is the inevitable destruction of the visible universe, unless we imagine this to be infinite, and so capable of endless degradation. 195. If, however, we continue to dwell upon this astounding phenomenon, we begin to perceive that we are not entitled to assert that this luminous energy does nothing but continue to travel outwards. It is perhaps too much to say that Struve’s speculations prove an ethereal absorption, but they must be taken in connection with other considerations. We have already maintained (Art. 151), that we cannot regard the ether as a perfect fluid. Now it is not easy to suppose that in such a substance all vibratory motion should pass outwards without in the smallest degree becoming absorbed or changing its type. We are prepared doubtless to expect a great difference between the ether and visible matter in this respect, but can hardly imagine that it is absolutely free from the capacity of altering the type of the energy which passes through it. Such a hypothesis appears to us to violate the principle of continuity. 196. But we may go even further than luminiferous vibrations which take their rise chiefly at the surfaces of bodies, and extend our speculations into the interior of substances, since the law of gravitation assures us that any displacement which takes place in the very heart of the earth will be felt throughout the universe, and we may even imagine that the same thing will hold true of those molecular motions (Art. 56) which accompany thought. For every thought we think is accompanied by a displacement and motion of the particles of the brain, and we may imagine that somehow these motions are propagated throughout the universe. Views of this nature were long ago entertained by Babbage, and they have since commended themselves to several men of science, and amongst others to Jevons. ‘Mr. Babbage,’ says this author,[57] ‘has pointed out[58] that if we had power to follow and detect the minutest effects of any disturbance, each particle of existing matter must be a register of all that has happened.’