or admits an accident—is the gross substance; whereas the subtle substance neither admits an accident nor occupies space, such as the substance of the soul, the substance of the intellect, and other similar subtle substances.
If, then, the created subtle substances admit no accident and occupy no space, shall the Creator of both the subtle and the gross substances, the One who unites the subtle with the gross, Himself admit an accident and occupy space? Never.
You have therefore declared explicitly that He is a substance that admits no accident, and you have said: “Nothing that exists is anything but substance or accident; whatever subsists by itself, needing no other for its existence, is substance, and whatever depends for its existence on another, having no independent subsistence, is accident.”
It may thus be asked of you: this eternal, pre-existent Son, born of the substance of His Father—born, not created, who became incarnate and descended—is He a substance subsisting by Himself, or an accident subsisting in another? According to your own principle, whatever exists is either substance or accident.
If you say, “He is a substance,” you have plainly affirmed two substances: the Father is a substance and the Son is a substance, and the hypostasis of life will then be a third substance. This is a clear admission of three independently subsisting substances.
At that point your claim is nullified that “He is one God, a single essence with three attributes, one in substance and three in hypostasis,” for on this reckoning you have openly affirmed three substances.