This hypothesis was developed in the 18th/19th century and proposes four authors
- J (Yahwist)
- E (Elohist)
- P (priestly)
- D (deuteronomist)
J and E are so-named because of the forms of the divine name that dominate in the passages ascribed to them. Most of the book of Leviticus, and other passages having to do with the operation of the sacrificial system, are ascribed to P.
For further information, see Wikipedia.