Wordsworth alludes to the opening chapter of Samuel Johnson’s The History of Rasselas, Prince of Abyssinia (1759): “The place which the wisdom or policy of antiquity had destined for the residence
of the Abyssinian princes was a spacious valley…surrounded on every side by mountains,
of which the summits overhang the middle part. The only passage by which it could
be entered was a cavern that passed under a rock.”