om the luminous body, it can be readily seen that
the intensity of light really implies a decrease of motion.

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 Gravita