heated by
Motion, because it stands still, and remains in the same posture, both
when the Sun shines upon it, and when it does not, and yet 'tis evident
to Sense, that there is a vast difference in it, in respect of Heat and
Cold, at those several times. Nor does the Sun first heat the Air, and
so the Earth; because we may observe in hot weather, that the Air which
is nearest the Earth, is hotter by much than that which is higher and
more remote. It remains therefore that the Sun has no other way of
heating the Earth but by its Light, for Heat always follows Light, so
that when its Beams are collected, as in Burning-Glasses for instance,
it fires all before it. Now 'tis Demonstrated in Mathematicks, that the
Sun is a Spherical Body, and so is the Earth; and that the Sun is much
greater than the Earth; and that part of the Earth which is at all times
illuminated by the Sun is above half of it; and that in that half which
is illuminated, the Light is most intense in the midst; both because
that part is the most remote from Darkness, which is the Circumference
of the Circle, as also, because it lies opposite to more parts of the
Sun: and that those parts which are nearest the Circumference of the
Circle, have less Light; and so gradually, till the Circumference of the
Circle, which encompasses the illuminated part of the Earth, ends in
Darkness.

Sec. 2. Now that is the Center of the Circle of Light, where the Sun is
Vertical to the Inhabitants, and then in that place, the Heat is most
extreamly intense; and so those Countries are the coldest, where the Sun
is farthest from being Vertical. And if there were any such place where
the Sun was always Vertical, it must needs be extream hot. Now 'tis
demonstrated in Astronomy, that the Sun is Vertical twice a Year only,
to those which live under the Equinoctial, _viz_. when he enters into
_Aries_ and _Libra_; and all the rest of the Year he declines from them,
six months Northward, and six months Southward; and for that reason they
are neither too hot nor too cold, but of a Moderate Temper between both.
There's much more to be said about this Argument, in order to the
explaining it fully, but it is not suitable to our purpose; I have only
hinted it to you, because it helps the Story a little, and makes it
something more probable that a Man may be form'd without the help of
Father and Mother; and there are some which affirm positively that _Hai
Ebn Yokdhan_ was so, others deny i