Wilkins, John, A discovery of a new world : or a discourse tending to prove, that 'tis probable there may be another Habitable World in the Moon ; with a discourse concerning the Probability of a Passage thither; unto which is added, a discourse concerning a New Planet, tending to prove, that 'tis probable our earth is one of the Planets

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That the Moon may be a World.
this Orb of vaporous Air, it might there reſt
immovable, and would not have in it any pro-
penſion to this motion of Deſcent.
For the better illuſtration of this, you muſt
know, that the heavineſs of a body, or (as
De cælo
lib.4.cap.1.
Ariſtotle defines it) the proneneſs of it to tend
down unto ſome Centre, is not any abſolute
quality intrinſical unto it, as if, whereever the
body did retain its Eſſence, it muſt alſo retain
this quality:
or as if Nature had emplanted in
every condenſed Body Appetitionem centri, &

fugam extremitatis.
Such a Love to the Cen-
tre, and hatred to the Extremities.
Becauſe
one of theſe being leſs than a quantity, and the
other no more, cannot have any power of At-
traction or Diſpulſion in them.
According to
that common principle, Quantitatis nulla eſt
efficacia.
But now the true nature of Gravity is this.
A magne-
tical natu-
ral axtra-
ction.
So Keplar
Somn.
Aſtron. N.
66.
Coper. l. 1.
cap. 26.
Foſcarin in
epiſt. ad
Sebaſt.
Fantonum.
’Tis ſuch a reſpective mutual deſire of Union,
whereby condenſed Bodies, when they come
within the Sphere of their own Vigour, do
naturally apply themſelves, one to another by
Attraction or Coition.
But being both with-
out the reach of eithers Virtue, they can ceaſe
to move, and though they have general Apti-
tude, yet they have not any preſent Inclinati-
on or proneneſs to one another.
And ſo con-
ſequently, cannot be ſtiled heavy.
The meaning of this will be clearly Illuſtra-
ted by a Simtlitude.
As any light Body
(ſuppoſe the Sun) does ſend forth his Beams
in an orbicular form;
ſo likewiſe any magneti-
cal Body, for inſtance, a round Load-ſtone does
Gilbert de
Maguete.
l. 2. cap. 7.
caſt abroad his magnetical Vigour in a Sphere.
Thus.

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