The Letter of Enoch is the fifth and final book of the five books that have survived in the Ge'ez language. Fragments of it have been found among the Dead Sea Scrolls, along with fragments of the Book of the Watchers, Book of Parables, and Dream Visions, proving it has circulated with them since at least the 3rd-century BC. It is very unlikely that the Letter of Enoch predates the 3rd-century BC, as it includes Greek philosophical ideas that unlikely to have been adopted before Alexander conquered the Persian Empire, and Greeks began ruling Judea. One of these ideas is the concept of the 'Word,' the 'first-born of God' who was accepted by Hellenistic Jews as being the 'Angel of the Lord' from the Septuagint translation of the Hebrew scriptures.
The general message of the Letter is very Zoroastrian in its message of good-versus-bad, light-versus-dark, and righteous-versus-dishonest. The author was clearly an outcast from the power-structure of the time, and constantly attacks against the 'wealthy' and 'powerful,' accusing them of being sinful. Whoever the author was, there are very few of the indicators from the Book of the Watchers and the Book of Parables which point to Canaanite and Babylonian origins for the text, and the little present can be explained as copying from the earlier texts. The identical description of the sky becoming seven times brighter when the end of the world comes is identical to the description found in the Book of Parables, which is otherwise anachronistic in the Book of Parables, as all other indicators point to a Jewish reworking of a Babylonian text, likely during the Babylonian era. This idea that the world would end in light when good/light conquered evil/darkness, is the central theme of Zoroastrianism, the official religion of the Persian Empire that ruled Judea between 525 and 333 BC. The identical description of the end of the world in the Book of Parables and the Letter of Enoch, suggests strongly that the author of the Letter was the same person that added the description of the end-of-the-world to the Book of Parables, likely at the same time that the 'Testament of Noah' was redacted into the surviving Book of Parables.
