namely, the earth; so that wheresoever the earth may be placed, or
whithersoever it may be carried by its animal faculty, heavy bodies will
always be carried towards it. If the earth were not round, heavy bodies
would not tend from every side in a straight line towards the centre of
the earth, but to different points from different sides. If two stones
were placed in any part of the world near each other, and beyond the
sphere of influence of a third cognate body, these stones, like two
magnetic needles, would come together in the intermediate point, each
approaching the other by a space proportional to the comparative mass of
the other. If the moon and earth were not retained in their orbits by
their animal force or some other equivalent, the earth would mount to
the moon by a fifty-fourth part of their distance, and the moon fall
towards the earth through the other fifty-three parts, and they would
there meet, assuming, however, that the substance of both is of the same
density. If the earth should cease to attract its waters to itself all
the waters of the sea would he raised and would flow to the body of the
moon. The sphere of the attractive virtue which is in the moon extends
as far as the earth, and entices up the waters; but as the moon flies
rapidly across the zenith, and the waters cannot follow so quickly, a
flow of the ocean is occasioned in the torrid zone towards the westward.
If the attractive virtue of the moon extends as far as the earth, it
follows with greater reason that the attractive virtue of the earth
extends as far as the moon and much farther; and, in short, nothing
which consists of earthly substance anyhow constituted although thrown
up to any height, can ever escape the powerful operation of this
attractive virtue. Nothing which consists of corporeal matter is
absolutely light, but that is comparatively lighter which is rarer,
either by its own nature, or by accidental heat. And it is not to be
thought that light bodies are escaping to the surface of the universe
while they are carried upwards, or that they are not attracted by the