_M._ I commend you; for, indeed, I could myself willingly be mistaken
in his company. Do we, then, doubt, as we do in other cases (though I
think here is very little room for doubt in this case, for the
mathematicians prove the facts to us), that the earth is placed in the
midst of the world, being, as it were, a sort of point, which they call
a [Greek: kentron], surrounded by the whole heavens; and that such is
the nature of the four principles which are the generating causes of
all things, that they have equally divided among them the constituents
of all bodies; moreover, that earthy and humid bodies are carried at
equal angles by their own weight and ponderosity into the earth and
sea; that the other two parts consist, one of fire, and the other of
air? As the two former are carried by their gravity and weight into the
middle region of the world, so these, on the other hand, ascend by
right lines into the celestial regions, either because, owing to their
intrinsic nature, they are always endeavoring to reach the highest
place, or else because lighter bodies are naturally repelled by
heavier; and as this is notoriously the case, it must evidently follow
that souls, when once they have departed from the body, whether they
are animal (by which term I mean capable of breathing) or of the nature
of fire, must mount upward. But if the soul is some number, as some
people assert, speaking with more subtlety than clearness, or if it is
that fifth nature, for which it would be more correct to say that we
have not given a name to than that we do not correctly understand
it--still it is too pure and perfect not to go to a great distance from
the earth. Something of this sort, then, we must believe the soul to
be, that we may not commit the folly of thinking that so active a
principle lies immerged in the heart or brain; or, as Empedocles would
have it, in the blood.