What did John Ruskin mean by the Lamp of Memory in architecture?

In his 1849 book The Seven Lamps of Architecture, John Ruskin defined the "Lamp of Memory" as a principle advocating for the scrupulous preservation and respect for the original fabric of historic buildings.1

Rather than viewing old structures as mere objects for restoration or replacement, Ruskin argued that their value lies in their authentic physical history. By emphasizing the importance of maintaining the integrity of these structures, he sought to protect the tangible connection between the past and the present. This moral stance on architectural conservation became a foundational influence on the 20th-century conservation movement and inspired figures such as William Morris.1