But this might also be due to something else which will, perhaps, shock Relativists, but will seem to Newtonians quite possible. The ether, the medium that transmits the luminous waves, and which Einstein has ended by admitting once more (refusing, however, to give it its familiar kinematic properties), and matter seem more and more to be merely modalities. We explained this, on the strength of the most recent physical discoveries, in a previous chapter. There is nothing to prove that these two forms of substance are not always associated. Does this not give me the right to think that perhaps our whole visible universe, our local concentration of matter, is only an isolated clump or sphere of ether? If there is such a thing as absolute space (which does not mean that it is accessible to us), it is independent of ether as well as matter. In that case there would be vast empty spaces, devoid of ether, all round our universe. Possibly other universes palpitate beyond these; and for us such worlds would be for ever as if they did not exist. No ray of knowledge would ever reach us from them. Nothing could cross the black, dumb abysses which environ our stellar island. Our glances are confined for ever within this giant—yet too small—monad. “Are there, then,” some will cry in astonishment, “things which exist, yet we will never know them?” Naive pretension—to want to embrace everything in a few cubic centimetres of grey brain-stuff! CHAPTER VIII SCIENCE AND REALITY _The Einsteinian absolute—Revelation by science—Discussion of the experimental bases of Relativity—Other possible explanations—Arguments in favour of Lorentz’s real contraction—Newtonian space may be distinct from absolute space—The real is a privileged form of the possible—Two attitudes in face of the unknown._ We approach the end of our work. Has reality, seen through the prism of science, changed its aspect with the new theories? Yes, certainly. The Relativist theory claims to have improved the achromatism of the prism and by this means improved the picture it gives us of the world. Time and space, the two poles upon which the sphere of empirical data turned, which were believed to be unshakeable, have been dislodged from their strong positions. Instead of them Einstein offers us the continuum in which beings and phenomena float: four-dimensional space-time, in which space and time are yoked together. But this continuum is itself only a flabby form. It has no rigidity. It adapts itself docilely to everything. There is nothing fixed, because there is no definite point of reference by means of which we could distribute phenomena; because on the shores of this great ocean in which things float there are none left of those solid rings to which mariners once fastened their vessels.