"I know what a forest is, and a mountain, and a sea," Stone agrees. "I don't know about Earth or Tamaris. I'm from the Reaches in the Three Worlds. Which is very obviously not here." With the idea of other whole worlds out there, he is no longer even considering that this might be some strange place made by the forerunners or their contemporaries. It doesn't smell right. None of the writing is right. Sure, the ancients had technology nobody understood, but it didn't look like this.