Happy Thanksgiving! This blog bills itself as “patristic, medieval, byzantine, anglican”, so here we go, in reverse order:
From the Book of Common Prayer:
ALMIGHTY God, Father of all mercies, We thine unworthy servants do give thee most humble and hearty thanks For all thy goodness and loving-kindness To us and to all men; [* particularly to those who desire now to offer up their praises and thanksgivings.] We bless thee for our creation, preservation, and all the blessings of this life; But above all for thine inestimable love In the redemption of the world by our Lord Jesus Christ; For the means of grace, And for the hope of glory. And we beseech thee, give us that due sense of all thy mercies, That our hearts may be unfeignedly thankful, And that we show forth thy praise, Not only with our lips, but in our lives; By giving up ourselves to thy service, And by walking before thee in holiness and righteousness all our days; Through Jesus Christ our Lord, To whom, with thee and the Holy Ghost, be all honour and glory, world without end. Amen.
From St Gregory Palamas (14th c):
Prayer changes from entreaty to thanksgiving, and meditation on the divine truths of faith fills the heart with a sense of jubilation and unimpeachable hope. This hope is a foretaste of future blessings, of which the soul even now receives direct experience, and so it comes to know in part the surpassing richness of God’s bounty, in accordance with the Psalmist’s words, ‘Taste and know that the Lord is bountiful’ (Ps. 34:8). For He is the jubilation of the righteous, the joy of the upright, the gladness of the humble, and the solace of those who grieve because of Him.
From St Francis of Assisi (13th c)
Almighty, most holy, most high and supreme God, holy and just Father, Lord, king of heaven and earth, for Thyself we give thanks to Thee 68because by Thy holy will, and by Thine only Son, Thou hast created all things spiritual and corporal in the Holy Ghost and didst place us made to Thine image and likeness in paradise, whence we fell by our own fault. And we give Thee thanks because, as by Thy Son Thou didst create us, so by the true and holy love with which Thou hast loved us, Thou didst cause Him, true God and true man, to be born…. And we give thanks to Thee because Thy Son Himself is to come again in the glory of His Majesty … to say to all who have known Thee and adored Thee, and served Thee in repentance: “Come, ye blessed of my Father, possess the Kingdom prepared for you from the beginning of the world.” And since all we wretches and sinners are not worthy to name Thee, we humbly beseech Thee, that our Lord Jesus Christ, Thy beloved Son, in whom Thou art well pleased, together with the Holy Ghost, the Paraclete, may give thanks to Thee as it is pleasing to Thee and Them, for all. Amen. (Prayers of the Middle Ages, ed. J. Manning Potts, 1956)
From John the Solitary (of Apamea, early 5th c., Syriac):
What is required of us is to give him thanks unceasingly — not indeed to the full extent that befits his gift, for no one is capable of giving him thanks as would be appropriate, for his grace is far greater than the thanksgiving of all peoples; it is enough for us to realize that we have not the ability either to repay him, or even to thank him sufficiently (Letter to Hesychius, trans. Sebastian Brock, The Syriac Fathers on Prayer and the Spiritual Life, pp. 83-83)