eing inhabited by rational beings, of an organisation
similar to those on the earth, it can have little force, when urged with
respect to rational beings in general.

"But we may examine without indulging too much in conjecture, whether
it be not possible that the planets may be possessed by rational beings,
and contain animals and vegetables, even little different from those
with which we are familiar.

"Is the sun the principal cause of the temperature of the earth? We have
reason to suppose that it is not. The mean temperature of the earth, at
a small depth from the surface, seems constant in summer and in winter,
and is probably coeval with its first formation.

"At the planet Mercury, the direct heat of the sun, or its power of
causing heat, is six times greater than with us. If we suppose the mean
temperature of Mercury to be the same as of the earth, and the planet
to be surrounded with an atmosphere, denser than that of the earth,
less capable of transmitting heat, or rather the influence of the sun to
extricate heat, and at the same time more readily conducting it to keep
up an evenness of temperature, may we not suppose the planet Mercury fit
for the habitation of men, and the production of vegetables similar to
our own?

"At the Georgium Sidus, the direct influence of the sun is 360 times
less than at the earth, and the sun is there seen at an angle not much
greater than that under which we behold Venus, when nearest. Yet may not
the mean temperature of the Georgium Sidus be nearly the same as that of
the earth? May not its atmosphere more easily transmit the influence of
the sun, and may not the matter of heat be more copiously combined, and
more readily extricated, than with us? Whence changes of season similar
to our own may take place. Even in the comets we may suppose no great
change of temperature takes place, as we know of no cause which will
deprive them of their mean temperature, and particularly if we suppose,
that on their approach towards the sun, there is a provision for
their atmosphere becoming denser. The tails they exhibit, when in the
neighbourhood of the sun, seem in some measure to countenance this idea.

"We can hardly suppose the sun, a body three hundred times larger than
all the planets together, was created only to preserve the periodic
motions, and give light and heat to the planets. Many astronomers have
thought that its atmosphere only is luminous, and its body opake, and
prob