5 The defect, therefore, of that passion which has regard to ignorance, will either attach alike to their whole Pleroma, since [all its members] are of the same substance; and the Propator will share in this defect of ignorance— that is, will be ignorant of Himself; or, on the other hand, all those lights which are within the Pleroma will alike remain for ever impassible. Whence, then, comes the passion of the youngest Æon, if the light of the Father is that from which all other lights have been formed, and which is by nature impassible? And how can one Æon be spoken of as either younger or older among themselves, since there is but one light in the entire Pleroma? And if any one calls them stars, they will all nevertheless appear to participate in the same nature. For if “one star differs from another star in glory,” but not in qualities, nor substance, nor in the fact of being passible or impassible; so all these, since they are alike derived from the light of the Father, must either be naturally impassible and immutable, or they must all, in common with the light of the Father, be passible, and are capable of the varying phases of corruption.
Source: Adversus haereses (New Advent)