How it is impossible for the devil to be reconciled.
Anselm. If you carefully consider the scheme of human salvation, you will perceive the reconciliation of the devil, of which you made inquiry, to be impossible. For, as man could not be reconciled but by the death of the God-man, by whose holiness the loss occasioned by man's sin should be made up; so fallen angels cannot be saved but by the death of a God-angel who by his holiness may repair the evil occasioned by the sins of his companions. And as man must not be restored by a man of a different race, though of the same nature, so no angel ought to be saved by any other angel, though all were of the same nature, for they are not like men, all of the same race. For all angels were not sprung from one, as all men were. And there is another objection to their restoration, viz., that, as they fell with none to plot their fall, so they must rise with none to aid them; but this is impossible. But otherwise they cannot be restored to their original dignity. For, had they not sinned, they would have been confirmed in virtue without any foreign aid, simply by the power given to them from the first. And, therefore, if any one thinks that the redemption of our Lord ought to be extended even to the fallen angels, he is convinced by reason, for by reason he has been deceived. And I do not say this as if to deny that the virtue of his death far exceeds all the sins of men and angels, but because infallible reason rejects the reconciliation of the fallen angels.