The modern practice of prayer, meditation, and study for Unity on the basis of our Lord’s words as they are recorded in the seventeenth chapter of St. John can be traced to the striking letter on the reunion of Christendom which Pope Leo XIII wrote in 1894, on his completion of fifty years of episcopal life. The aged Pontiff, who was to remain active for nearly ten more years, prefaced his appeal to Orthodox and Anglican, pagan and lapsed, with the following commentary :

‘As this Divine prayer embraces not only the souls who then believed in Jesus Christ, but also every one of those who were henceforth to believe in Him, it gives us an excellent reason for confidently expressing our hopes and for making all possible endeavours that men of every race and clime may be called and moved to embrace the unity of Divine faith.’