Tahafut_al-Tahafut-transl-Engl-van-den-Bergh

constitute the poles. But the differentiation of these two points, exclusive
of all other points which might just as well be the poles of this identical
sphere cannot happen except by a quality differentiating between two
similar objects. If the philosophers assert that it is not true that any other
place on the sphere might be the seat for these poles, they will be told:
such an assertion implies that the parts of the spheres are not
homogeneous and yet you have often said that the sphere is of a simple
nature and therefore has a simple form, viz. the spherical. And again, if
the philosophers affirm that there are spots on the sphere which are not
homogeneous, it will be asked how these spots came to be of a
heterogeneous nature; is it because they are a body or because they are
a celestial body? But the absence of homogeneity cannot be explained in
this way. Therefore-Ghazali says just as among philosophers the theory is
upheld that all times are equivalent in regard to the creation of the world,
the theologians are justified in claiming that the parts of heaven are
equivalent in regard to their serving as poles, and that the poles do not
seem differentiated from the other points through a special position or
through their being in an immovable place, exclusive of all other places.
This then in short is the objection; it is, however, a rhetorical one, for
many things which by demonstration can be found to be necessary seem
at first sight merely possible.’ The philosophers’ answer is that they assert
that they have proved that the world is composed of five bodies: a body
neither heavy nor light, i.e. the revolving spherical body of heaven and
four other bodies, two of which are earth, absolutely heavy, which is the
centre of the revolving spherical body, and fire, absolutely light, which is
seated in the extremity of the revolving sphere; nearest to earth is water,
which is heavy relatively to air, light relatively to earth; next to water
comes air, which is light relatively to water, heavy relatively to fire. The
reason why earth is absolutely heavy is that it is farthest away from the
circular movement, and therefore it is the fixed centre of the revolving
body; the reason why fire is absolutely light is that it is nearest to the
revolving sphere; the intermediate bodies are both heavy and light,
because they are in the middle between the two extremes, i.e. the farthest
point and the nearest. If there were not a revolving body, surely there
would be neither heavy nor light by nature, and neither high nor low by
nature, and this whether absolutely or relatively; and the bodies would not
differ by nature in the way in which, for instance, earth moves by nature to
63