 What does it mean, for Fârâbî, to say that X is the cause of existence to Y, or that X is the existence of Y, or that X enters into the constitution [qiwâm] of Y or is part of that by which the existence of Y is constituted? At first blush, the first sentence of the Perfect City, “the first being [mawjûd] is the first cause of existence [wujûd] to all other beings [mawjûdât]”, seems to be taking the position of al-Kindî that Fârâbî had criticized in the Book of Letters, according to which the first being, God, would be a separately existing existence-itself, such that everything else would come to exist by participating in it: things would exist [would be mawjûd] through an existence [wujûd] as they are white though a whiteness, and God would be that existence. Is he here, in the Perfect City, slipping into the kind of popularizing philosophy that he had criticized through a logical syntax of language in the Book of Letters? An immediate response is that Fârâbî’s position in the Perfect City is not the same as Kindî’s, since Fârâbî does not say that God is the existence of anything else. But we would still want to know how God is the cause of the existence of other things, and more generally what it means to say that X is the cause of the existence of Y, and what role this plays in Fârâbî’s argument in the Perfect City. And Fârâbî’s positive theory in the Book of Letters gives us resources for understanding this.