As thou, dearest friend,1 hadst enjoined us to bring forward the Valentinian opinions—hidden, as they think,—into open day; and to shew their diversities, and add some discourse in refutation of them: we accordingly have endeavoured to call them to account, setting forth their tenets and the derivations thereof, even from Simon the father of all heretics, and disputing against them all. With this view,—the exposure and overthrow of them, in many particulars, pertaining to one and the same task,—we have sent thee certain books; whereof the first contains the opinions of each of them, and their customs, and shews the chief features of their way of life.
In the second again, their evil doctrines are refuted and overturned, and stript bare, and displayed, such as they really are.
And in this third book we shall adduce evidence from the Scriptures:2 that nothing of what thou hadst required may be wanting on our part: rather thou mayest receive from us, even beyond thine anticipations, helps for the exposure and overthrow of those who in any way teach amiss. For the Charity which is in God, rich and ungrudging, bestows more than one requires of it.
Do thou then remember what we have said in the two former books; and adding the present thereunto, thou wilt have from us the fullest reply to all the Heretics, and with confidence and all earnestness wilt resist them, on behalf of the only true and life-giving Faith; which the Church hath received from the Apostles, and dispenses to her sons. For indeed the Lord of all gave to His Apostles the power of the Gospel; and by them we have known the Truth, i.e., the teaching of the Son of God: To whom also the Lord said,3 He that heareth you, heareth Me: and he that despiseth you, despiseth Me, and Him that sent Me.