These forms beheld in divine natures possess a fabricative power, but with us they are only gnostic, and no longer demiurgic, through the defluxion of our wings, or degradation of our intellectual powers. For, as Plato says in the Phaedrus, when the winged powers of the soul are perfect and plumed for flight, she dwells on high, and in conjunction with divine natures governs the world. In the Timaeus, he manifestly asserts that the demiurgus implanted these dianoetic forms in souls, in geometric, arithmetic, and harmonic proportions: but in his Republic (in the section of a line in the 6th book) he calls them images of intelligibles; and on this account does not for the most part disdain to denominate them intellectual, as being the exemplars of sensible natures. In the Phaedo he says that these are the causes to us of reminiscence; because disciplines are nothing else than reminiscences of middle dianoetic forms, from which the productive powers of nature being derived and inspired, give birth to all the mundane phenomena.
Plato however did not consider things definable, or in modern language abstract ideas, as the only universals, but prior to these he established those principles productive of science which essentially reside in the soul, as is evident from his Phaedrus and Phaedo. In the 10th book of the Republic too, he venerates those separate forms which subsist in a divine intellect. In the Phaedrus, he asserts that souls elevated to the supercelestial place, behold Justice herself, temperance herself, and science herself; and lastly in the Phaedo he evinces the immortality of the soul from the hypothesis of separate forms.
Syrianus[11], in his commentary on the 13th book of Aristotle's Metaphysics, shows in defense of Socrates, Plato, the Parmenideans, and Pythagoreans, that ideas were not introduced by these divine men according to the usual meaning of names, as was the opinion of Chrysippus, Archedemus, and many of the junior Stoics; for ideas are distinguished by many differences from things which are denominated from custom. Nor do they subsist, says he, together with intellect, in the same manner as those slender conceptions which are denominated universals abstracted from sensibles, according to the hypothesis of Longinus:[12] for if that which subsists is unsubstantial, it cannot be consubsistent with intellect.