Plotinos: Complete Works, v. 1 In Chronological Order,...

Souls therefore are necessarily amphibians;171 since they alternately live in the intelligible world, and in the sense-world; staying longer in the intelligible world when they can remain united to supreme Intelligence more permanently, or staying longer or preponderatingly here below when nature or destiny imposes on them a contrary fate. That is the secret meaning of Plato's words172 to the effect that the divinity divides the seeds of the souls formed by a second mixture in the cup, and that He separates them into (two) parts. He also adds that they must necessarily fall into generation after having been divided into a definite number. Plato's statement that the divinity sowed the souls,173 as well as the divinity's address to the other deities, must be taken figuratively. For, in reference to the things contained in the universe, this implies that they are begotten or produced; for successive enumeration and description implies an eternal begetting, and that those objects exist eternally in their present state.