Plotinos: Complete Works, v. 3 In Chronological Order,...

4. Apart from the exigencies of our argument, it may be interesting to consider whether there be any wastage off from heaven, so as to create a need of being (replenished or) fed, so to speak; or whether all its contents, being once for all established, subsist there naturally, without allowing any of their substance to escape. In the latter case we would be driven further to inquire whether the heaven be composed of fire exclusively or principally213; and whether, while dominating the other elements, the fire engages them in its course. Were we to associate (with fire) the Soul, which is the most powerful of all causes, so as to unite her with elements so pure and excellent (just as, in other animals, the soul chooses the best parts of the body as dwelling-place), we would have produced a solid argument for the immortality of the heaven. Aristotle indeed says that the flame surges, and that the fire devours everything with an insatiable avidity206; but he was evidently speaking only of the terrestrial fire, for the celestial fire is calm, immovable, and in harmony with the nature of the stars.