The dating of revelation
In setting up this quote from Irenaeus, he refers to the book as “what is called the Revelation of John,” indicating a degree of doubt as to whether John actually wrote it.More significantly, Eusebius elsewhere places Revelation in the category of “spurious books” (3.25).Personally, I think Irenaeus’s point makes better sense if ἑωράθη is translated “he was seen.” In that case, Irenaeus would be referring back to John himself and not to the revelation that John saw.
If Eusebius was only seeking to provide evidence for the more general claim that John was alive during Domitian’s reign, then his use of Irenaeus does nothing to support the late date of Revelation.
In terms of external evidence, there’s a quote from the church father Irenaeus (130–202 AD) that is often referenced in debates about the date of Revelation.
There are two questions I want to address here: (1) what Irenaeus actually said, and (2) what Eusebius thought Irenaeus said.
And just to belabor this point beyond what is necessary, here are a few of those examples: “And he was seen (ἑωράθη) by practically all mankind.
For there was no city of repute, and no nation, which he did not visit; and among all alike the same opinion of him prevailed — that they had seen no one more beautiful.” (Dio Chrysostom, Discourse 29, section 6) “In the capture of the city, no Theban was seen (ἑωράθη) begging the Macedonians to spare his life, nor did they in ignoble fashion fall and cling to the knees of their conquerors.” (Diodorus Siculus, Library of History, 17.13.2) “And when he came to the last hall, then he mounted a chariot, but sometimes he mounted a horse; but on foot he was never seen (οὐδέποτε ἑωράθη) outside of his palace.” (Athenaeus, Deipnosophists, 12.8) The point to draw from this is that only the context can determine whether ἑωράθη is best translated as “it was seen” or “he was seen.” And that’s what needs to be kept in mind when we’re interpreting Irenaeus’s use of the word.