Eusebius
Veneration

The earliest recorded feast day of Eusebius is found in the earliest known Syrian Martyrology dating to the year 411 translated by William Wright. The Martyrology lists his feast day as May 30. Eusebius continues to be venerated as a Saint by the modern-day Syrian Orthodox Church as well, with a feast day on February 29 according to the official calendar of Saints created by Corbishop Rajan Achen.

Eusebius was long venerated in the Roman Catholic Church. Bishop J.B. Lightfoot writes in his entry for St. Eusebius in Henry Wace 's Dictionary of Christian Biography and Literature to the End of the Sixth Century AD, with an Account of Principal Sects and Heresies (1911) that "in the Martyrologium Romanum itself he held his place for centuries" and in "Gallican service-books the historian is commemorated as a saint." However, Lightfoot notes that in "the revision of this Martyrology under Gregory XIII his name was struck out, and Eusebius of Samosata was substituted, under the mistaken idea that Caesarea had been substituted for Samosata by a mistake." The Roman Catholic author Henri Valois includes in his translations on Eusebius' writings testimonies of ancient authors in favor and against Eusebius, to which in the favor category he includes evidence of Eusebius in several martyrologies and being called a "Blessed" dating back to Victorius of Aquitaine. Valois includes both Usuardus and Notker, who list his feast as June 21 in the Roman Martyrology, and a Gallican breviary is included for June 21 that reads as follows:

Of the holy Eusebius, bishop and confessor. Lesson 1. Eusebius, bishop of Cæsarea in Palestine, on account of his friendship with Pamphilus the martyr, took from him the surname of Pamphili; inasmuch as along with this same Pamphilus he was a most diligent investigator of sacred literature. The man indeed is very worthy of being remembered in these times, both for his skill in many things, and for his wonderful genius, and by both Gentiles and Christians he was held distinguished and most noble among philosophers. This man, after having for a time labored in behalf of the Arian heresy, coming to the council of Nicæa, inspired by the Holy Spirit, followed the decision of the Fathers, and thereafter up to the time of his death lived in a most holy manner in the orthodox faith. Lesson 2. He was, moreover, very zealous in the study of the sacred Scriptures, and along with Pamphilus the martyr was a most diligent investigator of sacred literature. At the same time he has written many things, but especially the following books: The Præparatio Evangelica, the Ecclesiastical History, Against Porphyry, a very bitter enemy of the Christians; he has also composed Six Apologies in Behalf of Origen, a Life of Pamphilus the Martyr, from whom on account of friendship he took his surname, in three books; likewise very learned Commentaries on the hundred and fifty Psalms. Lesson 3. Moreover, as we read, after having ascertained the sufferings of many holy martyrs in all the provinces, and the lives of confessors and virgins, he has written concerning these saints twenty books; while on account of these books therefore, and especially on account of his Præparatio Evangelica, he was held most distinguished among the Gentiles, because of his love of truth he contemned the ancestral worship of the gods. He has written also a Chronicle, extending from the first year of Abraham up to the year 300 AD, which the divine Hieronymus has continued. Finally this Eusebius, after the conversion of Constantine the Great, was united to him by strong friendship as long as he lived.

A bone fragment relic of Eusebius within its original reliquary is on display at the Shrine of All Saints located within St. Martha's Catholic Church in Morton Grove, Illinois.
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