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

one occurred, they gave three answers to this question. Some, like
Anaxagoras and his school, believe that plurality is only introduced
through matter,’ some believe that plurality is introduced through the
instruments, and some believe that plurality comes only through the
mediators; and the first who assumed this was Plato. This is the most
convincing answer, for in the case of both the other solutions one would
have to ask again; from where does the plurality come in the matters and
in the instruments? But this difficulty touches anyone who acknowledges
that from the one only one can proceed: he has to explain how plurality
can derive from the one. Nowadays, however, the contrary of this theory,
namely, that out of the one all things proceed by one first emanation, is
generally accepted, and with our contemporaries we need discuss only
this latter statement.
The objection which Ghazali raises against the Peripatetics, that, if
plurality were introduced through mediators, there could only arise a
plurality of qualitatively undifferentiated agglomerates which could only
form a quantitative plurality, does not touch them. For the Peripatetics hold
that there exists a twofold plurality, the plurality of simple beings, those
beings namely that do not exist in matter, and that some of these are the
causes of others and that they all ascend to one unique cause which is of
their own genus, and is the first being of their genus, and that the plurality
of the heavenly bodies only arises from the plurality of these principles;
and that the plurality of the sublunary world comes only from matter and
form and the heavenly bodies. So the Peripatetics are not touched by this
difficulty. The heavenly bodies are moved primarily through their movers,
which are absolutely immaterial, and the forms of these heavenly bodies
are acquired from these movers and the forms in the sublunary world are
acquired from the heavenly bodies and also from each other, indifferently,
whether they are forms of the elements which are in imperishable prime
matters or forms of bodies composed out of the elements, and, indeed,
the composition in this sublunary world arises out of the heavenly bodies.
This is their theory of the order which exists in the world. The reasons
which led the philosophers to this theory cannot be explained here, since
they built it on many principles and propositions, which are proved in many
sciences and through many sciences in a systematic way. But when the
philosophers of our religion, like Farabi and Avicenna, had once conceded
to their opponents that the agent in the divine world is like the agent in the
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