Irenaeus of Lyons, Against Heresies 2.8

They will claim that this is the shadow of those realities, just as some among them dare to assert, so that, according to this logic, images must exist. It then becomes necessary for them to confess that the bodies themselves which are above are those very things. Bodies that are above cast a shadow, but spiritual things do not, since they cannot obscure anything. Even if we granted them this impossible concession—that spiritual and luminous things have a shadow, into which they say their Mother descended—the consequence remains: since those things are eternal, the shadow produced from them is perpetual. It endures and does not pass away, but perseveres together with the things that cast it. If, however, those shadows pass away, then the realities of which they are shadows must also pass away; but if the realities persevere, their shadow perseveres with them. If they say it is a shadow not according to what is overshadowed, but according to what is widely separated from them, they will accuse the smallness and weakness of their paternal light, as though it does not reach these realms but fails to fill what is empty and to dissolve the shadow—and this when no one stands in the way. According to them, their paternal light would be converted into darkness and be obscured; it would fail in those places of emptiness, since it is least able to fill all things.

Therefore they should no longer say that the Pleroma is the Bythos of all their realities; for what is empty and a shadow neither fills nor illuminates. Or else they should dismiss the shadow and the empty altogether, since their paternal light fills all things. Neither can the Pleroma, nor the first God who is above all, exist outside the first Father—that is, the God who is over all—into which they say the Enthymesis of the Aeons descended, so that it might not be defined and circumscribed by what is outside, and so that the Pleroma itself might be contained, or the first God. Nor can it be empty or receive a shadow, since the Father already exists, lest his light fail and be defined within emptiness. It is irrational and impious to invent a place where, according to them, the Propator and Proarche, the Father of all and of this Pleroma, ceases and has an end. Nor is it permissible to say that within the Father's bosom another being fabricated such a condition, whether with his consent or without it, for the reasons already stated. It is equally impious and foolish to claim that such a condition was fabricated by angels, or by some ignorant emission of the true God, within the realms that belong to him. Nor can those things which are earthly and base be brought into existence within their Pleroma, since it is a wholly spiritual universe. Nor is it possible even according to their own image: since they say that a few, similar formations are one, it cannot follow that things of many conditions and contrary to one another could be produced.

Their word, which comes from the shadow of the void—that is, of their vacuum—has proved false in every respect. Thus the void has been exposed as their fiction, and their doctrine as inconstant; and those who give heed to them are truly descending into the depths of perdition.