Of the old time entombed. (40)
The past isn't just gone; it's dead. In this line it's as if the "old time" has been symbolically laid away in a tomb, just like a dead body. What once was green and growing and cheerful is gone forever—just like death, the fall of the palace doesn't work backwards. We're stuck in this hideous new world forever and ever (or at least until we put the book down and go eat a tub of Ben and Jerry's to make ourselves feel better).