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

is partly the cause of unity, partly the cause of plurality. And since Aristotle
was the first to find this solution, and because of its difficulty, many of the
later philosophers did not understand it, as we have shown. It is evident,
therefore, that there is a unique entity from which a single power
emanates through which all beings exist. And since they are many, it is
necessarily from the Monad, in so far as it is one, that plurality arises or
proceeds or whatever term is to be used. This is the sense of Aristotle’s
theory, a sense very different from that in which those thinkers believe
who affirm that from the one only one can proceed. See therefore how
serious this error proved among the philosophers! You should, therefore,
see for youself in the books of the ancients whether these philosophical
theories are proved, not in the works of Avicenna and others who changed
the philosophical doctrine in its treatment of metaphysics so much that it
became mere guessing.
Ghazali says, on behalf of the philosophers:
It may be said: If the philosophical theory is properly
understood, the difficulties disappear. Existents can be
divided into what exists in a substratum, like accidents and
forms, and what does not exist in a substratum. The latter
can be divided again into what serves as a substratum for
other things, e.g. bodies, and what does not exist in a
substratum, e.g. substances which subsist by themselves.
These latter again are divided into those which exert an
influence on bodies and which we call souls, and those
which exert an influence not on bodies but on souls, and
which we call abstract intellects. Existents which inhere in a
substratum, like accidents, are temporal and have temporal
causes which terminate in a principle, in one way temporal,
in another way everlasting, namely, circular movement. But
we are not discussing this here. Here we are discussing only
those principles which exist by themselves and do not inhere
in a substratum, which are of three kinds: (i) bodies, which
are the lowest type, (ii) abstract intellects, which are not
attached to bodies, either by way of action or by being
impressed upon them, which are the highest type, and (iii)
souls, which are the intermediate agencies, attached to the
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