Now let us apply the law of inverse squares in relation to light to the solar system. We have the sun with its huge form all aglow with fires, as the source of all light to the planetary worlds that revolve around it. Year in and year out, for many ages past, the sun has been pouring out its light into space on every side, lighting up the planets or other bodies that revolve round it on that side only which is presented to the sun. Thus Mercury, at its distance of about 36,000,000 miles, obtains a light from the sun which is of far greater intensity than the light which Venus receives, while Venus receives a light of greater intensity than the light which the Earth receives, and the Earth receives light of greater intensity than any of the planets outside its orbit in the solar system, as Mars, Jupiter, Saturn, Uranus, or Neptune. This decrease in the intensity of light is according to the inverse square of the distance from the central body, the sun. So that if we have one planet at twice the distance from the sun, as compared with another planet, the intensity of light at that distance will be only 1/4 of the intensity received by the nearer planet. This decrease of the intensity of light, however, may be compensated for by a difference in the constituents of the planets' atmosphere, by means of which it may be possible that the outermost planets enjoy climatic conditions similar to our own. Now we have proved, in the previous chapter, that heat is a repulsive motion, and as the same aetherial waves give rise to the phenomena of light, then it ought to follow that light has equally a repulsive power on the planets with which it comes into contact. If that can be proved, and I submit that it can, then from the phenomena of light, we learn that there is a force, or rather a motion, ever proceeding from the sun in straight lines, as shown in the previous Art., which decreases in power or intensity inversely as the square of the distance. So that not only is the sun the centre of an attractive Force, the Centripetal force, or the attractive Force of Gravity, which proceeds in straight lines through space, decreasing in intensity inversely as the square of the distance, but at the same time it is also the centre of a motion, that is, the aetherial wave motion of light, which takes exactly the same path as Gravitation Attraction, and which is subject to exactly the same laws. Unlike Gravitation Attraction, however, its power and motion is ever directed away from the central body, the sun; and if such motion exerts any power on any planet with which it comes into contact, that power or motion can only be a repulsive motion in the same way that heat is a repulsive motion. Assuming, therefore, that light, through the medium of the aetherial waves, does exert this repulsive motion, then, according to the law of inverse squares, it can be seen that if a planet's distance be doubled, the repelling power of the aetherial light