The Priest cries aloud, “Lift up your hearts.” For truly ought we in that most awful hour to have our heart on high with God, and not below, thinking of earth and earthly things. In effect therefore the Priest bids all in that hour to dismiss all cares of this life, or household anxieties, and to have their heart in heaven with the merciful God. Then ye answer, “We lift them up unto the Lord:” assenting to it, by your avowal. But let no one come here, who could say with his mouth, “We lift up our hearts unto the Lord,” but in his thoughts have his mind concerned with the cares of this life. At all times, rather, God should be in our memory but if this is impossible by reason of human infirmity, in that hour above all this should be our earnest endeavour.
Then the Priest says, “Let us give thanks unto the Lord.” For verily we are bound to give thanks, that He called us, unworthy as we were, to so great grace; that He reconciled us when we were His foes; that He vouchsafed to us the Spirit of adoption. Then ye say, “It is meet and right:” for in giving thanks we do a meet thing and a right; but He did not right, but more than right, in doing us good, and counting us meet for such great benefits….
After this, we make mention of heaven, and earth, and sea; of sun and moon; of stars and all the creation, rational and irrational, visible and invisible; of Angels, Archangels, Virtues, Dominions, Principalities, Powers, Thrones; of the Cherubim with many faces: in effect repeating that call of David’s Magnify the Lord with me. We make mention also of the Seraphim, whom Esaias in the Holy Spirit saw standing around the throne of God, and with two of their wings veiling their face, and with twain their feet, while with twain they did fly, crying Holy, Holy, Holy, is the Lord of Sabaoth. For the reason of our reciting this confession of God, delivered down to us from the Seraphim, is this, that so we may be partakers with the hosts of the world above in their Hymn of praise. (St. Cyril of Jerusalem +386 A.D. : Cath Lecture 23)