after a while nobody , not even the sisters could remember what was real and what was not because even when they turned off the vr compilers sys 's creations stood as material and undeniable as the rest of the environment ; many of them bore uncanny resemblances to the enchanted emerald cave program or the training documentaries about the cultivation of soybeans , so there really was no telling whether what they saw was original , a photonic illusion or reconstituted matter .