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

philosophers cannot shake the conviction of their
adversaries that the eternal Will is connected with temporal
creation, except by claiming its absurdity by the necessity of
thought, and that therefore they are in no way different from
the theologians who make the same claim against the
philosophical doctrines opposed to theirs. And out of this
there is no issue.
I say:
Zaid and Amr are numerically different, but identical in form. If, for
example, the soul of Zaid were numerically different from the soul of Amr
in the way Zaid is numerically different from Amr, the soul of Zaid and the
soul of Amr would be numerically two, but one in their form, and the soul
would possess another soul. The necessary conclusion is therefore that
the soul of Zaid and the soul of Amr are identical in their form. An identical
form inheres in a numerical, i.e. a divisible, multiplicity, only through the
multiplicity of matter. If then the soul does not die when the body dies, or if
it possesses an immortal element, it must, when it has left the bodies,
form a numerical unity. But this is not the place to go deeper into this
subject.
His argument against Plato is sophistical. It says in short that the soul
of Zaid is either identical with the soul of Amr or different from it; but that
the soul of Zaid is not identical with the soul of Amr and that therefore it is
different from it. But ‘different’ is an equivocal term, and ‘identity’ too is
predicated of a number of things which are also called ‘different’. The
souls of Zaid and Amr are one in one sense and many in another; we
might say, one in relation to their form, many in relation to their
substratum. His remark that division can only be imagined of the
quantitative is partially false; it is true of essential division, but not of
accidental division, i.e. of those things which can be divided, because they
exist in the essentially divisible. The essentially divisible is, for example,
body; accidental division is, for instance, the division of whiteness, when
the bodies in which it is present are divided, and in this way the forms and
the soul are accidentally divisible, i.e. through the division of the substrate.
The soul is closely similar to light: light is divided by the division of
illuminated bodies, and is unified when the bodies are annihilated, and this
same relation holds between soul and bodies. To advance such
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