5. But how explain the permanence There, while the content of this sphere- its elements and its living things alike- are passing?
The reason is given by Plato: the celestial order is from God, the living things of earth from the gods sprung from God; and it is law that the offspring of God endures.
In other words, the celestial soul- and our souls with it- springs directly next from the Creator, while the animal life of this earth is produced by an image which goes forth from that celestial soul and may be said to flow downwards from it.
A soul, then, of the minor degree- reproducing, indeed, that of the Divine sphere but lacking in power inasmuch as it must exercise its creative act upon inferior stuff in an inferior region- the substances taken up into the fabric being of themselves repugnant to duration; with such an origin the living things of this realm cannot be of strength to last for ever; the material constituents are not as firmly held and controlled as if they were ruled immediately by a Principle of higher potency.
The heavens, on the contrary, must have persistence as a whole, and this entails the persistence of the parts, of the stars they contain: we could not imagine that whole to endure with the parts in flux- though, of course, we must distinguish things sub-celestial from the heavens themselves whose region does not in fact extend so low as to the moon.
Our own case is different: physically we are formed by that [inferior] soul, given forth [not directly from God but] from the divine beings in the heavens and from the heavens themselves; it is by way of that inferior soul that we are associated with the body [which therefore will not be persistent]; for the higher soul which constitutes the We is the principle not of our existence but of our excellence or, if also of our existence, then only in the sense that, when the body is already constituted, it enters, bringing with it some effluence from the Divine Reason in support of the existence.