  William argues that there must be a being by essence; otherwise, no being could be intelligible. Thus, if there were just beings by participation, there would have to be either a circle of beings each of which participates in the being of what is prior to it in the circle, with the absurd consequence that a thing would ultimately participate in its own being; or else there would have to be an infinite series of beings, each member of which participates in the being of what is prior in the series. But then, for a member of the series—say, A—to be, would be for it to have or participate in the being of B; and for B to be, in turn, would be for it to have or participate in the being of C, and so on. But if this were so, the being of no member of the series could be intelligible, since any attempt to spell it out would result in an account of the form: A's having B's having C's having ad infinitum. Since being is intelligible, William concludes that there is a being by essence.