Eos had isolated Reality from Limbo, doing so to prevent any outside influence over It, as he sought to cleanse it of the taint of the Primordials.
Nothing would be able to enter or exit this Reality. As he could not be sure about the overall state of existence since he had no method to investigate the Cradle of Enoch thoroughly, it may be possible that the life left inside Reality may be the last time creation left outside his control.
Eos did not want to create everything, and he saw the need for diversity and new mysteries outside his overall control. Existence would be meaningless if everything sprang from him.
However, progress can sometimes emerge from unexpected places and situations, and Eos had isolated Eosah's Reality for various purposes. Still, he could not anticipate that one of the final pieces of the puzzle keeping him from the ninth-dimensional level would reveal itself from this process.
