You have here, reverend Ambrosius, the conclusion of what we have been enabled to accomplish by the power given to us in obedience to your command. In eight books we have embraced all that we considered it proper to say in reply to that book of Celsus which he entitles A True Discourse. And now it remains for the readers of his discourse and of my reply to judge which of the two breathes most of the Spirit of the true God, of piety towards Him, and of that truth which leads men by sound doctrines to the noblest life. You must know, however, that Celsus had promised another treatise as a sequel to this one, in which he engaged to supply practical rules of living to those who felt disposed to embrace his opinions. If, then, he has not fulfilled his promise of writing a second book, we may well be contented with these eight books which we have written in answer to his discourse. But if he has begun and finished that second book, pray obtain it and send it to us, that we may answer it as the Father of truth may give us ability, and either overthrow the false teaching that may be in it, or, laying aside all jealousy, we may testify our approval of whatever truth it may contain.
Glory Be to You, Our God; Glory Be to You.
Source: Against Celsus (New Advent)