The Apocalypse of John
23 Nay more, the Epistle— for I pass by the Gospel— does not mention nor does it contain any intimation of the Apocalypse, nor does the Apocalypse of the Epistle. But Paul, in his epistles, gives some indication of his revelations, though he has not written them out by themselves.
24. Moreover, it can also be shown that the diction of the Gospel and Epistle differs from that of the Apocalypse.
25. For they were written not only without error as regards the Greek language, but also with elegance in their expression, in their reasonings, and in their entire structure. They are far indeed from betraying any barbarism or solecism, or any vulgarism whatever. For the writer had, as it seems, both the requisites of discourse—that is, the gift of knowledge and the gift of expression—as the Lord had bestowed them both upon him.
26. I do not deny that the other writer saw a revelation and received knowledge and prophecy. I perceive, however, that his dialect and language are not accurate Greek, but that he uses barbarous idioms, and, in some places, solecisms.
27. It is unnecessary to point these out here, for I would not have any one think that I have said these things in a spirit of ridicule, for I have said what I have only with the purpose of showing clearly the difference between the writings.
Source: Church History (New Advent)