[Footnote 6: The moon strongly, and more than any other agent, influences the tides. Apart from this effect the position of the moon has only a feeble influence upon the air pressure and upon atmospheric electricity and terrestrial magnetism. The influence of the stars is imperceptible.] In spite of the vehement enunciation of Giordano Bruno (1548-1600), this superstition was still deeply rooted when Newton succeeded in proving, in 1686, that the movements of the so-called wandering stars, or planets, and of their moons could be calculated with the aid of one very simple law: that all these celestial bodies are attracted by the sun or by their respective central bodies with a force which is proportional to their own mass and to the mass of the central body and inversely proportional to the square of their distance from that central body. Newton’s contemporary, Halley, applied the law of gravitation also to the mysterious comets, and calculating astronomy has since been based upon this, its firmest law, to which there has not been found any exception. The world was thus at once rid of the paralyzing superstition which exacted belief in a mysterious ruling of the stars. The contemporaries of Newton, as well as their descendants, have rightly valued this discovery more highly than any other scientific triumph of this hero’s. According to Newton’s law, all material bodies would tend to become more and more concentrated and united, and the development of the universe would result in the sucking up of the smaller celestial bodies—the meteorites, for instance—by the larger bodies. It must, however, be remarked that Newton’s great precursor, Kepler, observed in 1618 that the matter of the comets is repelled by the sun. Like Newton, he believed in the corpuscular theory of light. The sun and all other luminous bodies radiated light, they thought, because they ejected minute corpuscles of light matter in all directions. If, now, these small corpuscles hit against the dust particles in the comets’ tails, the dust particles would be carried away with them, and their repulsion by the sun would become intelligible. It is characteristic that Newton would not admit this explanation of Kepler’s, although he shared Kepler’s opinion on the nature of light. According to Newton, the deviation of the tails of comets from his law of general attraction was only apparent. The tails of comets, he argued, behaved like the columns of smoke rising from a chimney, which, although the gases of combustion are attracted by the earth, yet ascend because they are lighter than the surrounding air. This view, which has been characterized by Newcomb as no longer to be seriously taken into consideration, demonstrates the strong tendency of Newton to explain everything with the aid of his law.