Magic lamp
In short: The object that summons a genie in the tale of Aladdin.
Object
How does it work in the tale?
Its ordinary appearance conceals its power from those who do not know it. When it changes hands, someone else can use it and the conflict starts again.
Why does the old lamp change hands?
In Payne’s translation, the magician offers new lamps in exchange for old ones. To people in the palace who do not know what the lamp can do, the swap looks like a bargain. Readers know what the old lamp is worth. That gap in knowledge makes an ordinary offer dangerous.