He has also shown that the proper motions of stars would be greater if there were many more stars than those which we see. Thus Poincaré’s calculations are opposed to the hypothesis of an indefinite extension of the stellar universe, as the number of stars “counted” agrees fairly closely with the number “calculated.” We should add, however, that these calculations prove nothing if the law of attraction is not quite the inverse proportion of the square at enormous distances. On the other hand, if the universe is finite in space as it is conceived in classic science, the light of the stars, and isolated stars themselves, would gradually drift away into the infinite, and the cosmos would disappear. Our mind resents this consequence, and astronomical observation discovers no trace whatever of such a dislocation. In a word, in the space of the “Absolutists” the stellar universe can only be infinite if the law of the square of distances is not quite exact for very remote masses; and it cannot be finite except on the condition that it is ephemeral in point of time. For Newton, indeed, the _stellar_ universe might be finite within an infinite universe, because in his view there can be space without matter. For Einstein, on the contrary, the universe and the material or stellar universe are one and the same thing, because there is no space without matter or energy. * * * * * These difficulties and obscurities disappear in great part when we consider space, or space-time, from the Einsteinian standpoint of General Relativity. What is the meaning of the sentence, “The universe is infinite”? From either the Einsteinian, the Newtonian, or the Pragmatist point of view it means: If I go straight ahead, going on eternally, I shall never get back to my starting-point. Is it possible? Newton is compelled to say yes, because in his view space stretches out indefinitely, independent of the bodies that occupy part of it, whether the number of the stars is or is not limited. But Einstein says no. For the Relativist the universe is not necessarily infinite. Is it therefore limited, fenced in by some sort of railings? No. It is not limited. A thing may be unlimited without being infinite. For instance, a man who moves on the surface of the earth may travel over it indefinitely in every direction without ever reaching a limit. The surface of the earth, thus regarded, or the surface of any sphere whatsoever, is therefore both finite and unlimited. Well, we have only to apply to space of three dimensions what we find in two-dimensional space (a spherical surface), to see how the universe may be at one and the same time finite and unlimited.