But how is the nebula formed? The cluster in the constellation Hercules (Fig. 5), if it is not in fact a colossal nebula, shows that some of the stars are very close together. Now, these immense objects, that in blind fury dash through space, may come into collision with one another and explode into a nebulous cloud; or they may plough through dense swarms of meteorites, with a resultant explosion on a smaller scale; or, torn by internal convulsions, they may burst into fragments and scatter their dead dust over the abyss of space. In one or all of these ways the nebula is born, to begin again the recurring cycle of Nature’s life. [Illustration: FIG. 5.—THE CLUSTER IN HERCULES.] Is there further evidence of this? There is. On the night of February 21, in the year 1901, a luminous object appeared in the constellation Perseus. From a region where all was darkness the night before, a new and wondrous body now blazed forth its treasures of light. To the astronomers, who with lively curiosity watched the new birth for months, it meant that a tremendous conflagration had taken place in the heavens. A new nebula had been given to the universe, not, however, on the night when its light was first seen, but when Napoleon was dazzling the world with his victories; for the glowing mass was 500 billion miles away, and its messenger light, flying across space with the awful velocity of 186,000 miles a second, had been hurrying ninety-nine years to bring the news to our world! Science now warrants a further step—one which reveals the origin and nature of matter—the ultimate source of the nebula itself. Ether fills all space. It penetrates even the most solid substances. The universe of matter swims in an ocean of ether. Only by the presence of ether is the force of gravitation made possible—it must have ether upon which to act. The wings of ether alone transmit to us the light of the sun and stars. Now science is telling us that this indispensable ether, this infinitely attenuated and invisible substance, is the birthplace of matter—that atoms of matter are composed of minute centres of energy, or electrons, in ether. The atom is built of thousands of electrons whirling with inconceivable velocity in the space of their tiny, invisible universe; just as the visible universe is composed of myriads of suns and planets rushing forward through the boundless etherial ocean. Matter, then, whether nebulous or solid, was evolved out of the ether. [Illustration: GENERAL TABLE OF THE STRATIFIED SYSTEM AND FORMATIONS, ETC. FIG. 6.—A PILLAR OF STRATIFIED ROCKS. This illustration and others in this book are reproduced from Dennis Hird’s excellent work, “A Picture Book of Evolution,” with the kind permission of the publishers, Watts & Co., London.]