The Divided Line, 287.20 – 290.30
(Theosophically, the passage below could be considered to deal with the Astral Plane)
For the greater section can be considered to represent the intelligible world, it being superior to and encompassing the other, the lesser, which represents the visible world. For it is encompassed by this (section) according to cause. The encompassed is everywhere lesser than the encompassing, taken to be encompassed either by essence or according to actuality or according to potentiality, just as can be seen with all of the continuous and the divided.  Therefore, of the original unequal (sections) of the line, the greater is the genus of the intelligible world, and the other, the lesser, the genus of the visible world. And he related this,beginning with the genus of the visible, so that it is recognized first.
The other section of this division natures is comprised of images, and all the rest exist according to the images. From the activity of the images, moreover, which signify sculptures and paintings and everything of that nature, he divides the things to be emanated from the images, like the enlightened things are produced by the enlighteners, calling these images shadows and reflections in the water and other mirrors. And when defining what is needed to go into the body of the mirrors, he specifies denseness, smoothness and brightness. For denseness is needed so that the reflection that falls upon the pores is not lost in the many formations of the emanations of the forms. Therefore all the images of the visible have a specific nature and, in a certain manner, essence by virtue of the forms that they manifest as. As for the smoothness, so that the roughness by the nooks and crannies is not a cause of unevenness in the coming to be of the formation. Of the brightness, so that the image, the nature of which brings obscurity to the form, is nevertheless visible. For like the particles that are seen floating through a ray of light through a window, they are invisible without light, their own composition making them invisible.
Now from these considerations of ours, and according to Plato, the reflections will be some kind of manifested image of an essence produced by divine artifice, just as he teaches in the Sophist. As for the shadows, of which the images are the form, he said, they have this nature. And as for material things, they will be both images of shapes, and have very much sympathy with the things from which they are descended. And this is shown to us by accounts of the arts of the magicians which have reached us concerning shades and phantoms. And what to say of the activity of the shades? Actually, the idea can already be seen with irrational animals, before any other account. For the hyena, they say, when treading on the shadow of a dog sitting on high, the dog is stricken down and so the dog is make into a meal. And when a woman being cleansed (menstruating), says Aristotle (On Dreams 459b27), looks in a mirror, the mirror and the reflected image become blood-red. So the shades are also substantial realities, according to Plato, and the gist of the analogy is clear. For he says that the images have the same relation to the visible, as the intellectual has to the intelligible, therefore these images have some kind of form and real being.
 Ousia, energeia, and dunamis are terms derived from Aristotle’s Physics, of course here having a more Neoplatonic meaning.
 Sunekes, continuous, is a geometric term used in Aristotle’s Physics. Proclus tends to equate this with the concept of indivisibility. According to Opsomer: “This inference presupposes that every unmoved thing is indivisible. However, this hidden premise is not warranted by the previous arguments. Proclus has so far merely argued that everything indivisible is unmoved, not the other way around. Proclus tacitly introduces the equations: the incorporeal = the indivisible = the unmoved; the corporeal = the divisible = the moved” (195).
 Here he is making reference to the image of the shadows projected on the walls, in the Myth of the Cave from Republic, book VII.
 A rather free rendering, based on Kroll (290 n. 27).
 I take this somewhat cryptic passage to describe how things manifest themselves by an emanation from a pure archetype in the intelligible, then taking a kind of ethereal form in the world of psyche, which is an intermediate order between the ideal realm and the material world before manifesting in embodied physical form.
 I take this to refer to practices of summoning various departed souls and spiritual beings of some sort or causing apparitions.
 A similar account can be found in Aelian h.a. VI 14 (Kroll 290).
 A similar account can be found in Pliny VIII 106 (Kroll 290).