1. By the Reasons of Augustine and Avicenna

97. The second part I prove by Augustine On the Trinity VII ch.5 n.10: “It is manifest that God is improperly called a ‘substance’.” - His reason there is that substance is said to be that which stands under the accidents; but it is absurd to say that God stands under any accident;     therefore etc     . This reason holds in this way: Augustine does not understand that the idea of substance is ‘to stand under accidents as substance is a genus’, because he has given there as premise that “it is absurd that substance be said relatively.” But substance, as it is a genus, is limited, as will be immediately proved next [nn.101-107]; but every limited substance is able to receive an accident;     therefore any substance that is in a genus can stand under some accident, - God does not so stand, therefore etc     .

98. Again, Avicenna Metaphysics VIII ch.4 (99rb) argues that God is not in a genus, because a genus is a ‘part’; but God is simple, not possessing part and part; therefore God is not in a genus.

99. These two reasons [nn.97-98] are true by authority and reason together.