In Walden, Thoreau alludes to classical sources, the Bible, and great English authors. It would be as common among the educated audiences that Thoreau was addressing to know Greek literature, the Bible, and Shakespeare as it is today to understand such as allusions as "we're not in Kansas anymore."
An example of Biblical allusion in Walden is "it would be like keeping new wine in old bottles." This is a slightly altered reference to Jesus's statement in three of the Gospels that it ruins both the wine and wineskin to try to reuse an old wineskin. This is a metaphor in which Jesus tries to explain why he has abandoned old rituals, such as fasting. In Thoreau's case, he is saying people should literally wear their old clothes until they feel so inwardly changed that it would seem strange to keep the old clothes on. Like Jesus, he means that transformation should be inward, not a matter of outward ritual.
An example of an allusion to Shakespeare is "the winter of man's discontent." This is a...
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