the productions of the soil, have the same effect: they afford
agreeable cooling shades, and a moist atmosphere from their continual
exhalations, by which the ardour of the sun is considerably abated.
While the soil, on the other hand, if of a sandy nature, retains the
heat in an uncommon degree, and makes the summers considerably hotter
than those which are found to exist in the same latitude, where the soil
is different. To this proximity of what may be termed _burning
sands_, and to the sulphurous and metallick particles, which are
continually exhaling from the bowels of the earth, is ascribed the
different degree of blackness, by which some _African_ nations are
distinguishable from each other, though under the same parallels. To
these observations we may add, that though the inhabitants of the same
parallel are not exactly of the same hue, yet they differ only by shades
of the same colour; or, to speak with more precision, that there are no
two people, in such a situation, one of whom is white, and the other
black. To sum up the whole--Suppose we were to take a common globe; to
begin at the equator; to paint every country along the meridian line in
succession from thence to the poles; and to paint them with the same
colour which prevails in the respective inhabitants of each, we should
see the black, with which we had been obliged to begin, insensibly
changing to an olive, and the olive, through as many intermediate
colours, to a white: and if, on the other hand, we should complete any
one of the parallels according to the same plan, we should see a
difference perhaps in the appearance of some of the countries through
which it ran, though the difference would consist wholly in shades of
the same colour.

The argument therefore, which is brought against the hypothesis, is so
far from being, an objection, that we shall consider it one of the first
arguments in its favour: for if _climate_ has really an influence
on the _mucous substance_ of the body, it is evident, that we must
not only expect to see a gradation of colour in the inhabitants from the
equator to the poles, but also different[085] shades of the same colour
in the inhabitants of the same parallel.

To this argument, we shall add one that is incontrovertible, which is,
that when the _black_ inhabitants of _Africa_ are transplanted
to _colder_, or the _white_ inhabitants of _Europe_ to _hotter_
climates, their children, _born there_, are of a _different