1 The cause, then, of such a dispensation on the part of God, is to be inquired after; but the formation of the world is not to be ascribed to any other. And all things are to be spoken of as having been so prepared by God beforehand, that they should be made as they have been made; but shadow and vacuity are not to be conjured into existence. But whence, let me ask, came this vacuity [of which they speak]? If it was indeed produced by Him who, according to them, is the Father and Author of all things, then it is both equal in honour and related to the rest of the Æons, perchance even more ancient than they are. Moreover, if it proceeded from the same source [as they did], it must be similar in nature to Him who produced it, as well as to those along with whom it was produced. There will therefore be an absolute necessity, both that the Bythus of whom they speak, along with Sige, be similar in nature to a vacuum, that is, that He really is a vacuum; and that the rest of the Æons, since they are the brothers of vacuity, should also be devoid of substance. If, on the other hand, it has not been thus produced, it must have sprang from and been generated by itself, and in that case it will be equal in point of age to that Bythus who is, according to them, the Father of all; and thus vacuity will be of the same nature and of the same honour with Him who is, according to them, the universal Father. For it must of necessity have been either produced by some one, or generated by itself, and sprung from itself. But if, in truth, vacuity was produced, then its producer Valentinus is also a vacuum, as are likewise his followers. If, again, it was not produced, but was generated by itself, then that which is really a vacuum is similar to, and the brother of, and of the same honour with, that Father who has been proclaimed by Valentinus; while it is more ancient, and dating its existence from a period greatly anterior, and more exalted in honour than the remaining Æons of Ptolemy himself, and Heracleon, and all the rest who hold the same opinions.
2. But if, driven to despair in regard to these points, they confess that the Father of all contains all things, and that there is nothing whatever outside of the Pleroma (for it is an absolute necessity that, [if there be anything outside of it,] it should be bounded and circumscribed by something greater than itself), and that they speak of what is without and what within in reference to knowledge and ignorance, and not with respect to local distance; but that, in the Pleroma, or in those things which are contained by the Father, the whole creation which we know to have been formed, having been made by the Demiurge, or by the angels, is contained by the unspeakable greatness, as the centre is in a circle, or as a spot is in a garment, — then, in the first place, what sort of a being must that Bythus be, who allows a stain to have place in His own bosom, and permits another one to create or produce within His territory, contrary to His own will? Such a mode of acting would truly entail [the charge of] degeneracy upon the entire Pleroma, since it might from the first have cut off that defect, and those emanations which derived their origin from it, and not have agreed to permit the formation of creation either in ignorance, or passion, or in defect. For he who can afterwards rectify a defect, and does, as it were, wash away a stain, could at a much earlier date have taken care that no such stain should, even at first, be found among his possessions. Or if at the first he allowed that the things which were made [should be as they are], since they could not, in fact, be formed otherwise, then it follows that they must always continue in the same condition. For how is it possible, that those things which cannot at the first obtain rectification, should subsequently receive it? Or how can men say that they are called to perfection, when those very beings who are the causes from which men derive their origin— either the Demiurge himself, or the angels— are declared to exist in defect? And if, as is maintained, [the Supreme Being,] inasmuch as He is benignant, did at last take pity upon men, and bestow on them perfection, He ought at first to have pitied those who were the creators of man, and to have conferred on them perfection. In this way, men too would verily have shared in His compassion, being formed perfect by those that were perfect. For if He pitied the work of these beings, He ought long before to have pitied themselves, and not to have allowed them to fall into such awful blindness.
3. Their talk also about shadow and vacuity, in which they maintain that the creation with which we are concerned was formed, will be brought to nothing, if the things referred to were created within the territory which is contained by the Father. For if they hold that the light of their Father is such that it fills all things which are inside of Him, and illuminates them all, how can any vacuum or shadow possibly exist within that territory which is contained by the Pleroma, and by the light of the Father? For, in that case, it behooves them to point out some place within the Propator, or within the Pleroma, which is not illuminated, nor kept possession of by any one, and in which either the angels or the Demiurge formed whatever they pleased. Nor will it be a small amount of space in which such and so great a creation can be conceived of as having been formed. There will therefore be an absolute necessity that, within the Pleroma, or within the Father of whom they speak, they should conceive of some place, void, formless, and full of darkness, in which those things were formed which have been formed. By such a supposition, however, the light of their Father would incur a reproach, as if He could not illuminate and fill those things which are within Himself. Thus, then, when they maintain that these things were the fruit of defect and the work of error, they do moreover introduce defect and error within the Pleroma, and into the bosom of the Father.
Source: Adversus haereses (New Advent)