Short answer. Jubilees is a Jewish text from around 160-150 BCE that retells Genesis and early Exodus as a revelation dictated to Moses by an "angel of the presence." It reorganizes the Torah on a 364-day solar calendar and explains the origin of evil: demons are the spirits of the dead Giants, led by the prince Mastema. It is canonical scripture only in the Ethiopian Orthodox Tewahedo Church.
A retold Torah called "Little Genesis"
Jubilees covers the same ground as Genesis 1 through Exodus 14, but rewrites it: adding chronology, law, and angelic backstory the biblical text leaves out. Ancient writers called it Leptogenesis, "Little Genesis", a label variously read as marking its lesser authority beside canonical Genesis or its finer-grained detail (the book is in fact longer, not shorter). James VanderKam, the field's leading editor and translator (The Book of Jubilees, 2001; critical edition 2018), dates it to roughly 160-150 BCE on linguistic and historical grounds, and notes that fragments of at least fourteen or fifteen manuscripts turned up among the Dead Sea Scrolls at Qumran: making it one of the most copied books in that library, treated there with near-scriptural authority.
The framing device matters. The whole book is presented as a second revelation: God commands "the angel of the presence" to dictate the heavenly tablets to Moses (Jubilees 1:27-2:1). This lets the author insert observances (the Sabbath, festivals, circumcision) back into the patriarchal age, claiming they were always written in heaven. The agenda is priestly and reformist: it argues, against the Hellenizing currents of its day, that the covenant's calendar and purity laws are eternal and non-negotiable.
Mastema and the demons born from the dead Giants
Jubilees gives the clearest early "origin of evil" story in Second Temple literature, and it builds directly on the Watchers tradition from 1 Enoch 6-16. The fallen angels descend, take human wives, and father the Giants (Jubilees 5:1-2; compare Genesis 6:1-4). When the Giants die in the Flood, their spirits do not. They become the demons: disembodied, malicious, loose on the earth.
After the Flood these spirits begin to corrupt and kill Noah's grandchildren, and Noah prays for relief (Jubilees 10:1-6). Here the figure of Mastema (Hebrew maśṭēmâ, "animosity" or "hostility") steps forward as their chief and petitions God: let a portion remain under his command to do his will (Jubilees 10:8). God orders nine-tenths bound in the place of judgment and permits one-tenth to stay subject to Mastema (Jubilees 10:9-11). Mastema functions as a prosecutorial adversary: it is he, not God, whom Jubilees blames for the command to kill the firstborn and for testing Abraham at the binding of Isaac (Jubilees 17:16; 48:2-3). That move (peeling the dark deeds off God and assigning them to a named adversarial prince) is a real conceptual bridge toward the later figure of Satan: raw material the later tradition built on, not a proven line of descent (see Alan Segal, Two Powers in Heaven, 1977, on this period's experiments with a second power).
The 364-day calendar and the war over time
Jubilees insists on a solar year of exactly 364 days: twelve months plus four "days of remembrance," with the year cleanly divisible by seven into fifty-two weeks (Jubilees 6:23-32). Because 364 divides evenly by 7, every festival falls on the same weekday every year and never on a Sabbath. The author treats this calendar as revealed law and curses those who follow the moon, warning they will "disturb all their days" and keep the feasts on the wrong dates (Jubilees 6:36-38).
This was not a neutral astronomy lesson. As VanderKam and others have shown, the same 364-day system appears in the Astronomical Book of 1 Enoch (chapters 72-82) and in calendar texts from Qumran, a marker of a priestly faction at odds with the lunar reckoning that won out in mainstream Judaism. To get the calendar wrong, for Jubilees, is to celebrate holy days on profane time. The polemic tells you the book was a partisan document in a live dispute, not a quiet commentary.
Why it survived only in Ethiopia
Jubilees was composed in Hebrew, translated into Greek, then into Latin and Ge'ez (classical Ethiopic). Almost all of the Hebrew is lost; the only complete surviving text is the Ge'ez Mäṣḥafä Kufale ("Book of Division"), preserved by the Ethiopian Orthodox Tewahedo Church, supplemented by the Qumran fragments and partial Latin and Syriac witnesses. VanderKam's standard edition is built largely on those Ethiopic manuscripts.
Its canon status is unusually clean to state:
- Ethiopian Orthodox Tewahedo Church: fully canonical Old Testament scripture (alongside 1 Enoch).
- Rabbinic Judaism: never canonized; its solar calendar and angelology were on the losing side.
- Catholic, Eastern Orthodox, and Protestant traditions, not canonical; classed as Old Testament pseudepigrapha.
So Jubilees is "scripture" in exactly one living church, and an invaluable historical witness everywhere else.
Common questions
Why is Jubilees called "Little Genesis"?
Ancient writers called it Leptogenesis, "Little Genesis," a label variously read as marking its lesser authority beside canonical Genesis or its finer-grained detail. The "little" is not about length: the book is in fact longer than Genesis, not shorter. It covers the same ground as Genesis 1 through Exodus 14 but rewrites it, adding chronology, law, and angelic backstory the biblical text leaves out.
Who is Mastema in the Book of Jubilees?
Mastema (Hebrew maśṭēmâ, "animosity" or "hostility") is the chief of the demons. After the Flood he petitions God to let a portion of the demonic spirits remain under his command, and God binds nine-tenths while permitting one-tenth to stay subject to him (Jubilees 10:8-11). He functions as a prosecutorial adversary: it is he, not God, whom Jubilees blames for the command to kill the firstborn and for testing Abraham at the binding of Isaac.
How are demons explained in Jubilees?
Jubilees gives the clearest early "origin of evil" story in Second Temple literature, building directly on the Watchers tradition from 1 Enoch 6-16. The fallen angels descend, take human wives, and father the Giants (Jubilees 5:1-2); when the Giants die in the Flood, their spirits do not, and they become the demons, disembodied and malicious, loose on the earth. That move, peeling the dark deeds off God and assigning them to a named adversarial prince, is raw material the later tradition built on, not a proven line of descent to Satan.
What is the 364-day calendar in Jubilees?
Jubilees insists on a solar year of exactly 364 days: twelve months plus four "days of remembrance," cleanly divisible by seven into fifty-two weeks (Jubilees 6:23-32). Because 364 divides evenly by 7, every festival falls on the same weekday every year and never on a Sabbath. The author treats this as revealed law and curses those who follow the moon, and the same system appears in the Astronomical Book of 1 Enoch and in Qumran calendar texts, marking a priestly faction at odds with the lunar reckoning that won out in mainstream Judaism.
Jubilees does not prove that later Satan-and-demon theology was borrowed from anywhere. What it shows, from a dated text, is that Jews two centuries before Christ were already naming an adversarial prince and explaining evil as the residue of a cosmic fall, the raw material from which later traditions built.
Sources
Book of Jubilees Prologue; 1:27-2:1; 5:1-2; 6:23-38; 10:1-11; 17:16; 48:2-3 (trans. James C. VanderKam). Genesis 6:1-4. 1 Enoch 6-16; 72-82. James C. VanderKam,* The Book of Jubilees (2001) and critical edition (2018). Alan F. Segal, Two Powers in Heaven *(1977).