The Athenaeum is a storehouse for every dream from every mind on every world. It can only be accessed on the nearest instant of death, and even then, most people are only allowed to see the their own dreams. The previous Doctor (Jeroen) said, "That's not your life flashing before your eyes. It's your first and final page-through of your stored dreams." Thus far, the only person ever to steal a "book" from this library has been Chimera, and with it he was able to alter reality, bringing in heroes and villains from another universe.