But that proves nothing, as Olbers’ argument is wrong, for two reasons. On the one hand, there are necessarily a good many extinct or dark stars in the heavens. Some of them have been closely studied, even weighed. They betray their existence by periodically eclipsing brighter stars, with which they revolve. On the other hand, it was discovered some time ago that celestial space is occupied over large stretches by dark gaseous masses and clouds of cosmic dust, which absorb the light of more distant stars. We thus see that the existence of an infinite number of stars is quite compatible with the poorness of the light of the heavens at night. * * * * * Now let us put on our spectacles—our telescopes, I mean—and turn from the province of possibility to that of reality, and we shall see that recent astronomical observation has yielded a number of remarkable facts which lead irresistibly to the following conclusions. The number of the stars is not, as was long supposed, limited by the range of our telescopes alone. As we get further away from the sun, the number of stars contained in a unity of space, the frequence of the stars, the density of the stellar population, do not remain uniform, but decrease in proportion as we approach the limits of the Milky Way. The Milky Way is a vast archipelago of stars, our sun lying in its central region. This mass of stars, to which we belong, has, roughly, the shape of a watch-case, the thickness being only about half the width of the structure. Light, which travels from the earth to the moon in little over a second, from the earth to the sun in eight minutes, and from the earth to the nearest star in three years, needs at least 30,000 years—three hundred centuries—to pass from end to end of the Milky Way. The number of stars in the Milky Way is something between 500 and 1,500 millions. It is a small number: scarcely equal to the human population of the earth, much smaller than the number of molecules of iron in a pin’s head. In addition to these we have discovered dense masses of stars, such as the Magellanic Clouds, the cluster in Hercules, and so on, which seem to belong to the fringes of our Milky Way—to be suburbs of it, so to say. These suburbs seem to stretch a considerable distance, particularly on one side of the Milky Way. The furthest away is, perhaps, not less than 200,000 light-years from us. Beyond these, space seems to be deserted, devoid of stars over expanses which are enormous in comparison with the dimensions of our galactic universe as we have described it. What is beyond this?