The book begins With a Dream-Vision of Enoch. In this dream Enoch is asked to intercede for the watchers of heaven, i.e. the angels, who had left their heavenly home to commit iniquity with the daughters of men. He writes out the petition (cp. the title “Enoch the Scribe”) the fallen angels make, and then retires to await the answer, which comes to him in a series of visions. These visions are not quite easy to follow; they are evidently incomplete and somewhat confused; in all probability the text has suffered in transmission. At any rate, the petition is refused; Enoch declares to the fallen angels the doom which, as he has been taught in the visions, is to be their lot; the final words of the message which he is bidden to give them are: “You have no peace” (xii.-xvi.). […]
The book was thought to have been lost, for over 2,000 years, with many ancient sources referring to it, and even quoting parts, but no complete copies were known. Then in 1773, James Bruce brought three copies back from Ethiopia, having spent some years exploring the country.
Enoch had two main reasons for writing his book. The first was because the Watchers instructed him to do it, (see section 15 at 81.5 and 81.6). The second reason; was to save his family from the flood.
Enoch wrote his book, after his grandson Lamech was born, but before Noah was born. Noah is only named in the section that Methuselah wrote, (see section 10 at 107.3), and of course in his own section (section 11, The Book of Noah). So, there may still have been 40 – 80 years left before the flood, at the time when Enoch wrote his book. […]