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

We say:
The philosophers tried to acquire knowledge about reality through
speculation alone, without relying on the words of anyone who should
induce them to acquiesce in them without proof; on the contrary,
sometimes through speculation they came into contradiction with the facts
as shown by the senses. They discovered that the sublunary world can be
divided into two classes, the living and the inanimate, any instance of
which only comes into being through something, called form, which is the
entity by which it comes into being after having been non-existent; through
something, called matter, out of which it comes into being; through
something, called the agent, from which it comes into being; and through
something, called the end, for the sake of which it comes into being; and
so they established that there are four causes. And they found that the
form by which a thing comes into being, i.e. the form of the thing
generated, is identical with the proximate agent, from which it comes into
being, either in species, like the generation of man out of man, or in
genus, like the generation of the mule from a horse and a donkey. And
since, according to them, the causes do not form an infinite series, they
introduced a primary, permanent efficient cause. Some of them believed
that the heavenly bodies are this efficient cause, some that it is an
abstract principle, connected with the heavenly bodies, some that it is the
First Principle, some again that it is a principle inferior to it,’ and these
philosophers thought it sufficient to regard the heavens and the principles
of the heavenly bodies as the cause for the coming into being of the
elements, since according to them they too need an efficient cause. As to
the generation of living beings from each other in the sublunary world, the
philosophers had, because of this faculty of life, to introduce another
principle, which was the bestower of soul and of form, and of the wisdom
which is manifested in this world. This is what Galen calls the formative
faculty’ and some regard it as an abstract principle, some as an intellect,
some as a soul,’ some as the body of the heavens, and some as the First.
Galen called this potency the demiurge and was in doubt whether it is God
or another principle. This faculty acts in the generative animals and in
plants, and is needed still more in those plants and animals which have an
equivocal generation. This was the point they reached in the examination
of the sublunary world.
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