What type of connection is made when the reader of a biography about a famous figure discovers insight into a particular period of history?

text-to-self
text-to-text
text-to-world
text-to-event

In this excerpt from "colonialism in the united states" by henry c. lodge, which word is closest in meaning to the word indelibly? long after the world to which it belonged has vanished, a habit of thought will live on, indelibly imprinted upon a race or nation, like the footprint of some extinct beast or bird upon a piece of stone.