Kœstler (1959/79: 97-9):
It was a walled-in universe like a walled-in medieval town. In the centre lies the earth, dark, heavy and corrupt, surrounded by the concentric spheres of the moon, sun, planets, and stars in an ascending order of perfection, up to the sphere of the primum mobile, and beyond that the Empyrean dwelling of God.
But in the hierarchies of values, which is attached to this hierarchy of space, the original simple division into sub-lunary and supra-lunary regions has now yielded to an infinite number of sub-divisions. The original, basic difference between coarse, earthly mutability and ethereal permanence is maintained; but both regions are sub-divided in such a manner that the result is a continuous ladder, or graded scale, which stretches from God down to the lowliest form of existence. …
The […] theory was put into a more specifically Christian shape in The Celestial Hierarchy and The Ecclesiastical Hierarchy by the second most influential among the Neoplatonists, known as the pseudo-Dionysius. … It was he who provided the upper reaches of the ladder with a fixed hierarchy of angels, which were afterwards attached to the star-spheres to keep them in motion: the Seraphim turning the Primum Mobile, the Cherubim the sphere of fixed stars, the Thrones the sphere of Saturn; the Dominations, Virtues, and Powers the spheres of Jupiter, Mars, and the sun; the Principalities and Archangels the spheres of Venus and Mercury, while the lower angels look after the moon.
If the upper half of the ladder was Platonic in origin, the lower rungs were provided by Aristotelian biology, which was rediscovered around A.D. 1200. Particularly important became his 'principle of continuity' between apparently divided realms of nature…
The 'principle of continuity' made it not only possible to arrange all living beings into a hierarchy according to criteria such as 'degrees of perfection', 'powers of soul' or 'realisation of potentialities' (which, of course, were never exactly defined). It also made it possible to connect the two halves of the chain — the sub-lunary and the celestial — into a single continuous one, without denying the essential difference between them. …
The chain, thus unified, now reached from God's throne down to the meanest worm. It was further extended downward through the four elements into inanimate nature. … A further downward extension led into the conic cavity in the earth, around whose narrowing slopes the nine hierarchies of devils were arranged in circles, duplicating the nine heavenly spheres; Lucifer, occupying the apex of the cone in the precise centre of the earth, marked the bitter end of the chain.
The medieval universe, as a modern scholar remarked, is thus not really geocentric, but 'diabolocentric'.
Note that, in terms of metafunction, the ideal/real distinction is, of course, an ideational distinction, not a textual one.
