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

And as to the term `substance’ which the philosophers give to that which
is separate from matter, the First has the highest claim on the term
`substance’, the terms `existent’, `knowing’, `living’, and all the terms for
the qualities it bestows on the existents and especially those attributes
which belong to perfection, for the philosophers found that the proper
definition of substance was what existed by itself and the First was the
cause of everything that existed by itself.
To all the other reproofs which he levels against this doctrine no
attention need be paid, except in front of the masses and the ordinary
man, to whom, however, this discussion is forbidden.
And as to Ghazali’s words:
What beauty can there be in mere existence which has
no quiddity, no essence, which observes neither what occurs
in the world nor what is a consequence or proceeds from its
own essence? . . .
-this whole statement is worthless, for if the philosophers assume a
quiddity free from a substratum it is also void of attributes, and it cannot be
a substratum for attributes except by being itself in a substratum and
being composed of the nature of potency and the nature of act. The First
possesses a quiddity that exists absolutely, and all other existents receive
their quiddity only from it, and this First Principle is the existent which
knows existents absolutely, because existents become existent and
intelligible only through the knowledge this principle has of itself; for since
this First Principle is the cause of the existence and intelligibility of
existents, of their existence through its quiddity and of their intelligibility
through its knowledge, it is the cause of the existence and intelligibility of
their quiddities. The philosophers only denied that its knowledge of
existents could take place in the same way as human knowledge which is
their effect, whereas for God’s knowledge the reverse is the case. For they
had established this superhuman knowledge by proof. According to the
Ash’arites, however, God possesses neither quiddity nor essence at all
but the existence of an entity neither possessing nor being a quiddity
cannot be understood, ‘ although some Ash’arites believed that God has a
special quiddity by which He differs from all other existents, ‘ and
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