Simplify the following text for a Grade 12 native English-speaking person.
Original: Origen listed Lamentations and the Letter of Jeremiah as one unit with the Book of Jeremiah proper , among `` the canonical books as the Hebrews have handed them down , '' though scholars agree that this was surely a slip .
Simplified: Origen listed Lamentations and the Letter of Jeremiah as one unit with the Book of Jeremiah proper , among `` the canonical books as the Hebrews have handed them down '' .