As anyone who's read the Pearl of Great Price (specifically the Book of Moses) knows, Enoch, great-grandfather of Noah, is a far more significant figure in the Church of Jesus Christ of Latter-day Saints than in most other Christian churches (where his entire description runs to four verses in Genesis 5 and one attributed quote in Jude 1:14-15; in contrast, we have two chapters of prophesy attributed to him). I say most, because there's one exception: the Ethiopian Orthodox Church, who have a version of the Book of Enoch in their canonical scriptures.
This is the book which was quoted by Jude, or at least it includes Jude's quote. According to scholars, it was written around 300 BC, which makes it pseudoepigraphical (literally a "false inscription"), as that's rather later than Enoch's dates. However, there's no reason why it couldn't be based on earlier oral tradition. So I'm going to do an analysis of it.
Not the whole thing, of course -- it runs to over a hundred chapters. I'm just going to look at the first section, the Book of the Watchers. In fact, I'm only going to do the first half of that -- the second half is Enoch's journeys through Earth and Sheol (which is variously rendered "hell" or "the grave"). But I'm still covering 16 chapters, so this will be a multi-part post.
I'll take my text from this web site, and probably won't quote it in its entirety; however, I'll link to each chapter as I go, so you know what I'm referring to. I'm not a fan of uncheckable references.