His later days were spent writing about the danger
His later days were spent writing about the danger of pollution in the future in such works as The Storm Cloud of the Nineteenth Century, but also saw the discussion of times past with his autobiography, Praeterita.  His reasons for going mad are explained in his letters to laborers, Fors Clavigera.  Works like Unto This Last differed from his three major publications, which were influenced by his trips to Italy.  Two of those three are The Stones of Venice and The Seven Lamps of Architecture.  FTP, name this English art critic best known for his Modern Painters.
His later days were spent writing about the danger of pollution in the future in such works as The Storm Cloud of the Nineteenth Century, but also saw the discussion of times past with his autobiography, Praeterita.  
John Ruskin