JJ Abrams helpfully put three metaphors for TROS into the movie itself.

1) a scene in which a character combs through some ruins from the original trilogy in search of a macguffin that will lead to that trilogy's villain

2) the reanimated corpse of the original trilogy's villain dangling from the strings of a giant machine, like a marionette

3) a scene in which a character returns from beyond the grave to explicitly disavow his actions from the previous film