The natural opening leading from this broad enclosure, was about five hundred feet wide, and walled on either side by gigantic fragments of stone, from whose huge posterns it seemed as if in an earlier age of the world an immense gate may have swung and shut in captives of mighty size and fearful guilt. Nothing could be conceived a more secure and dreadful prison than these vast walls of rock: and no solitude could be more dreary than one thus fortified as it were by nature, and made sublimely desolate by barriers and enclosures like these.

Part Second, pages 115-116