E02794: A letter of Gregory the Great, written in Latin in Rome in 598, to Eulogios, Patriarch of Alexandria, regrets that there is no copy in Rome of the martyrdom accounts collected by Eusebius of Caesarea requested by Eulogios, but only a book with a few Martyrdoms in it. Gregory does have a book, with a list of saints' martyrdoms arranged by the day of the year, which he uses in the mass to honour them; this book records their names, places of martyrdom and feast days, from many different regions, but no further details about the saints.

Pope Gregory the Great, Register of Letters 8.28 ('Utilis semper est', JE 1517/JH 2606)

Utilis semper est docti viri allocutio, quia aut discit audiens quod nescire sese noverat aut cognoscit, quod est amplius, id quod se et nescisse nesciebat. Qua in re ex audientum numero ego nunc factus sum, cui sanctissima vestra beatitudo scribere studuit ut cunctorum martyrum gesta, quae piae memoriae Constantini temporibus ab Eusebio Caesariense collecta sunt, transmittere debeamus. Sed haec neque si sic collecta sint neque si sint ante vestrae beatitudinis scripta cognovi. Ago ergo gratias, quia sanctissimae doctrinae vestrae scriptis eruditus coepi scire quod nesciebam. Praeter illa enim quae in eiusdem Eusebii libris de gestis sanctorum martyrum continentur nulla in archivo huius nostrae ecclesiae vel in Romanae urbis bibliothecis esse cognovi, nisi pauca quaedam in unius codicis volumine collecta. Nos autem paene omnium martyrum distinctis per dies singulos passionibus collecta in uno codice nomina habemus atque cotidianis diebus in eorum veneratione missarum sollemnia agimus. Non tamen in eodem volumine quis qualiter sit passus indicatur, sed tantummodo nomen, locus et dies passionis ponitur. Vnde fit ut multi ex diuersis terris atque prouinciis per dies, ut praedixi, singulos cognoscantur martyrio coronati. Sed haec habere uos beatissimos credimus. Ea uero quae transmitti uoluistis quaerentes quidem non inuenimus, sed adhuc non inuenientes quaerimus et, si potuerint inueniri, transmittimus.

'An address from a learned man is always profitable, because the hearer either learns what he had known himself to be ignorant of, or, what is more, comes to know what he did not know he had been ignorant of. A hearer of the latter kind I have now become, your most holy Blessedness having been minded to write to me, asking me to send you the acts (gesta) of all the martyrs, which were collected in the times of Constantine, of pious memory, by Eusebius of Cæsarea. But before receiving the letter of your Blessedness I did not know of these acts, whether they had been collected, or whether not. I therefore give thanks that, instructed by your most holy teaching, I have begun to know what I was ignorant of. For beside what is contained about the acts of the holy martyrs in the books of the same Eusebius, I am not aware of any collections in the archives of this our Church, or in the libraries of the city of Rome, unless it be some few things collected in one single volume. We have however the names of almost all the martyrs, with their martyrdoms assigned to particular days, collected in one volume; and we celebrate the solemnities of mass on such days in their veneration. Yet it is not indicated in this volume who each was, and how he suffered; but only his name, the place, and day, of his martyrdom are put down. Hence it results that many of various countries and provinces are known to have been crowned with martyrdom, as I have said, through their several days. But these we believe you have. That, however, which you wish to have sent to you we have sought for, but have not found; but, though we have not found it, we will still search, and, if it can be found, will send it.'

Text: Norberg 1982, 549-550. Translation: Barmby 1895, slightly adapted.