, even if only as a condition, then the substrate is a cause. Yet they claim that the essence receives its existence; it would therefore be a cause of its own existence, contradicting their position.

Upon careful examination, however, an essence or one of its attributes may be a condition for another attribute. Were we among those who hold that an essence distinct from its existence is present in external reality, we would allow that the essence could be a condition for its existence. A condition need not precede what is conditioned, whereas a cause precedes its effect. But since nothing exists in external reality except the existence that is itself its own essence, there can be no essence there that either is or is not a condition for its own existence.

Then Ibn Sīnā said, in setting out their account of divine unity: “If the individuated Necessary Existent is individuated as such because it is necessarily existent, then there is no other necessary existent. If its individuation is not due to that, but to something else, then it is an effect. For if the necessity of existence is a necessary concomitant of its individuation, then necessity would be a necessary concomitant of an essence other than itself, or of an attribute, and that is impossible. If it is incidental, it has all the more reason to depend on a cause. And if that by which it is individuated