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??? (Theories) on This World is a book in the Violet Area in the game Ib. It is located in the middle bookcase of the lower-right wall of the library.

Ib and Mary cannot read some of its contents, even if Garry is with them. Garry can only read it by himself. If Mary looks at it, she will stare silently.


"Via a trading of ??? (existences), the ??? (imaginary) can be made reality."


This book references Mary's ultimate goal. As one of Guertena's paintings, ergo an imaginary being, she can only escape into the real world by switching places with someone from the outside. She planned to sacrifice Garry to achieve this goal.