To maintain "the sublime"
In the old sense.
The sublime “in the old sense” probobaly looked something like this…
That being noted, the speaker perhaps refers to Romanticism, which is renown for tending toward such nature as pictured above.
This is may also be a specific reference to Longinus‘ work, On the Sublime, a 1st-3rd c. Roman work—whose exact author is unknown. The text is about writing well and its effect, which hearkens back to an earlier period in rhetoric (in the Roman Republic, ancient Greece, etc.), which to the author was more pure (simple/powerful).
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