17.  Have thou ever in thy mind this seal The Benedictine Editor argues from Cat. i. 5, “that thou mayest by faith seal up the things that are spoken;” and xxiii. 18:  “sealing up the Prayer by the Amen,” that Cyril means by “this seal” the firm belief of Christian doctrine.  Compare John iii. 33.  But Milles understands by the “seal” the Creed itself, which agrees better with the following context., which for the present has been lightly touched in my discourse, by way of summary, but shall be stated, should the Lord permit, to the best of my power with the proof from the Scriptures.  For concerning the divine and holy mysteries of the Faith, not even a casual statement must be delivered without the Holy Scriptures; nor must we be drawn aside by mere plausibility and artifices of speech.  Even to me, who tell thee these things, give not absolute credence, unless thou receive the proof of the things which I announce from the Divine Scriptures.  For this salvation which we believe depends not on ingenious reasoning ἡ σωτηρία γὰρ αὕτη τῆς πίστεως ἡμῶν, which might be rendered, “this our salvation by faith,” or, with Milles, “this safety of our Faith.”  For the rendering in the text compare Heb. iii. 1:  ἀρχιερέα τῆς ὁμολογίας ἡμῶν.  On εὑρεσιλογία, see Polybius xviii. 29, § 3:  διὰ τῆς προς ἀλλήλους εὑρεσιλογίας., but on demonstration of the Holy Scriptures.