This text is written in Common and is entitled On Magical Entrapments, written by Thaelrythyn of Thay, dated 1345 DR. It appears to contain a summary of various kinds of magic designed to entrap a person's spirit or soul. A key passage reads as follows:
On Magical Entrapments
...Many spells exist which can tear a subject's spirit from its body, or its remains. Magic jar is one such spell, an incantation which traps a creature's spirit in an object until it can inhabit a new host. Certain magic items can be crafted to contain a soul, some of them enchanted so the holder of the container (be it a jar, a casket, a locket, or some other enclosed object) has power over the soul within. A spirit so trapped has no choice but to obey its captor until the item breaks or it is otherwise released...