God may give instructions through the medium of these heavenly messengers, and who act as the seer's guide. God may also personally give a revelation, as is shown in the Book of Revelation through the person of Jesus Christ.
There is hardly an example of a true Apocalypse in which the instrumentality of angels in giving the message is not made prominent.
In the Assumption of Moses, which consists mainly of a detailed prediction of the course of Israelite and Jewish history, the announcement is given to Joshua by Moses, just before the death of the latter.
So, too, in the Sibylline Oracles, which are for the most part a foretelling of future events, the Sibyl is the only speaker. Neither of these books are truly representative of apocalyptic literature in the narrower sense (see below).