Nature

Nature is neither Soul nor matter/material form.

However, there is an essence between them.

Matter/material form is inferior because it has been divided among bodies and lacks the capacity of being converted to self.

Nature surpasses all things that come after it because it contains the reason and productive principles found in them. Nature generates and vivifies. Nature tends towards bodies and is inseparable from them.

Nature is the last of the causes that fabricate corporeal bodies and sensible essence. She is also the boundary of the extent of incorporeal essence. 

Nature is full of reason and power through which she governs mundane beings.

Nature is a Goddess because she is worshipped, but she does not possess the immediate subsistence of a deity.

She governs the whole world, which contains the heavens in the summit of self, from where she rules over generation and weaves together partial natures at the extremities with wholes all around.

Nature is not confined by measure, and she is said to proceed directly from Rhea, the vivific goddess from whom all life originates—both intellectual life and that which cannot be separated from the governance of Nature.

Because Nature is suspended from Rhea, she traverses all things without impediment. She breathes into all things so that, through her, even the most inanimate beings participate in a particular soul. And such corruptible things will remain perpetually in the world, held together by the causes of forms she contains.

Nature, Self, is illuminated by the Gods and leads the universe, and the universe is always satisfied.

Plato, The Timaeus and the editor of Classical Philosophy.org