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 principally[213]; 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 avidity[206]; 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. THE HEAVEN'S IMMORTALITY ALSO DUE TO THE UNIVERSAL SOUL'S SPONTANEOUS MOTION. A still more important reason for the immortality of the heaven is that the universal Soul, moving with remarkable spontaneity, immediately succeeds the most perfect principles (such as the Good, and Intelligence). She could not therefore allow the annihilation of anything which had once been posited within her. Ignorance of the cause that contains the universe could alone permit denial that the universal Soul which emanates from the divinity excels all other bonds in strength. It is absurd to believe that after having contained something during a certain period, she could ever cease doing so. This would imply that she had done so till now by some violence; which would again infer the existence of some plan more natural than the actual state, and actual admirable disposition of beings within the very constitution of the universe; which would lastly suggest a force capable of destroying the organization of the universe, and of undermining the sovereignty of the governing Soul. THE IMMORTALITY OF THE HEAVEN PROVED BY ITS NEVER HAVING HAD TO BEGIN.