On the Mysteries (De Mysteriis)

...adapted for governance, and naturally provides for living beings, being affected now by some forms, now by others. Likewise, the Gods possess an order derived from higher causes, as well as Beauty itself, or rather the cause of both The "cause of both" refers to the source of both order and beauty; the soul, however, possesses order and an intellectual beauty. Furthermore, in the Gods there is a measure original: mensura; a principle of limit or regulation that is powerful over all things; but the soul determines that measure and acts through it only in certain specific things.

Demons and heroes, as intermediaries between the Gods and souls, are composed in a fitting proportion relative to those extremes and to themselves; they are formed from the properties of both souls and Gods, which we have described above. If you wish, therefore, to understand the nature original: speciem; referring to the essential form or kind of being of the Gods, consider the properties of the lowest rational soul and attribute their opposites, in a state of perfection, to the Gods. If you wish to construct the nature of a demon, compose it from both but attribute more of divinity to it. If, finally, you seek the nature of a hero, compose it from both, yet introduce more of the soul’s conditions.

He Iamblichus, the author criticizes PorphyryPorphyry of Tyre (c. 234–305 AD) was a Neoplatonic philosopher. Iamblichus wrote this text as a response to a letter from Porphyry, often correcting his more materialistic or Aristotelian interpretations of the divine. for distinguishing these separate beings according to their relationship to physical bodies—specifically, defining Gods by their relationship to ethereal bodies, demons to aerial bodies, and souls to terrestrial bodies—because, clearly, primary things and causes should not be defined by secondary things and effects. Incorporeal substances are not contained within bodies; rather, they lead them from the outside, giving something to them but receiving nothing from them.