Bede's Ecclesiastical History of England, ed. by A.M. Sellar, , at sacred-texts.com
IN the year of our Lord 582, Maurice, the fifty-fourth from Augustus, ascended the throne, and reigned twenty one years. In the tenth year of his reign, Gregory, a man eminent in learning and the conduct of affairs, was promoted to the Apostolic see of Rome, and presided over it thirteen years, six months and ten days. He, being moved by Divine inspiration, in the fourteenth year of the same emperor, and about the one hundred and fiftieth after the coming of the English into Britain, sent the servant of God, Augustine, and with him divers other monks, who feared the Lord, to preach the Word of God to the English nation. They having, in obedience to the pope’s commands, undertaken that work, when they had gone but a little way on their journey, were seized with craven terror, and began to think of returning home, rather than proceed to a barbarous, fierce, and unbelieving nation, to whose very language they were strangers; and by common consent they decided that this was the safer course. At once Augustine, who had been appointed to be consecrated bishop, if they should be received by the English, was sent back, that he might, by humble entreaty, obtain of the blessed Gregory, that they should not be compelled to undertake so dangerous, toilsome, and uncertain a journey. The pope, in reply, sent them a letter of exhortation, persuading them to set forth to the work of the Divine Word, and rely on the help of God. The purport of which letter was as follows:
"Gregory, the servant of the servants of God, to the servants of our Lord. Forasmuch as it had been better not to begin a good work, than to think of desisting from one which has been begun, it behoves you, my beloved sons, to fulfil with all diligence the good work, which, by the help of the Lord, you have undertaken. Let not, therefore, the toil of the journey, nor the tongues of evil-speaking men, discourage you; but with all earnestness and zeal perform, by God’s guidance, that which you have set about; being assured, that great labour is followed by the greater glory of an eternal reward. When Augustine, your Superior, returns, whom we also constitute your abbot, humbly obey him in all things; knowing, that whatsoever you shall do by his direction, will, in all respects, be profitable to your souls. Almighty God protect you with His grace, and grant that I may, in the heavenly country, see the fruits of your labour, inasmuch as, though I cannot labour with you, I shall partake in the joy of the reward, because I am willing to labour. God keep you in safety, my most beloved sons. Given the 23rd of July, in the fourteenth year of the reign of our most religious lord, Mauritius Tiberius Augustus, the thirteenth year after the consulship of our lord aforesaid, and the fourteenth indiction."