Proclus composed 18 arguments for the eternity of the world and they survive only because Philoponus, intending to refute Proclus' arguments one by one, quotes each; one copy of Philoponus' work – and so Proclus' arguments too – survives. Because of their odd history, these arguments have received little attention either in themselves or in relation to Proclus' other works, even though they are intrinsically interesting and reflect his larger philosophical enterprise. I first examine Argument XVIII, in which Proclus calls on "perpetuity", "eternity", and "time" to argue that the cosmos must be eternal. This argument leaves unanswered two important questions. The cosmos is caused by god and is itself a god; how can a cause and its effect both be gods? Proclus concludes that the cosmos is "a copy of the perpetuity of the eternal"; but what does this phrase – and the conclusion that it expresses – mean? To answer these questions, I turn to The Elements of Theology, a systematic progression of 211 propositions disclosing the causal structure of all reality. "Eternity" and "time", along with "being perpetual", also appear here, particularly in propositions 40-55, to which I turn in the second part of this paper. They are conjoined with what Proclus calls "the Self-Constituted". I argue that by understanding the relation of the Self-Constituted as a cause to its effect, what depends upon another, we can also understand the causal relation between god and the cosmos. The cosmos can be called divine because, via the cause/effect relation between them, god and the cosmos are both eternal; the cosmos is "a copy of the perpetuity of the eternal" because via its relation to god, the cosmos becomes what its cause is, and in this precise sense an effect "imitates" its cause.
Efforts to date Aristotle’s writings generally turn to their content, e.g., notions such as matter or actuality. This turn leads to the identification of this notion as early and that notion as late and so Aristotle’s writings can be dated and his development identified. I suggest that there is a better way to think about this problem. Ancient Greece witnesses the development of writing and, consequently, the shift from oral culture to a “book [or scroll] culture” and I argue that considering the material conditions of writing reveals the structure of ancient texts. Against this background, I turn to Aristotle’s Physics as a sequence of topics. Aristotle himself distinguishes “common and universal” topics, i.e., motion, the continuous, the infinite, place, void, and time, and “special attributes” that must be investigated after “common and universal” topics. The remainder of the Physics considers these topics. Although Aristotle never identifies an investigation of “special attributes”, a case can be made that the De Caelo and the De Generatione et Corruptione provide this investigation. And so we can understand the organization of the Aristotelian corpus as reflecting the organization of physics as a science: first the investigation of common and universal topics, and then the investigation of “special attributes”. But there is a problem with this view: book-body is common to all natural things but absent from the list of universal and common topics. In the Physics, Aristotle mentions but never examines body, as he investigates “things that are by nature”. In the De Caelo, he defines physics as the science of book-body and investigates body. Either this construal of Aristotle’s writing is wrong, or body is an anomaly within the ordering of topics, or body is a “special attribute”. This paper considers this question, concluding that body is in fact a “special attribute” (a point supported by analysis of the structure of Aristotle’s writing) and that it functions as a generic for physics only when abstracted from natural things.