Room 17: Canaletto's hugely popular 18th-century vedute (views) of Venice were aristocratic precursors of modern postcards; in such works as Island of San Giorgio Maggiore, Francesco Guardi achieved both poetry and melancholy.
Despite the beauty of Canaletto's works, they never became popular. 
mnli hypothesis: Despite the beauty of Canaletto's works, they never became popular.  premise: Room 17: Canaletto's hugely popular 18th-century vedute (views) of Venice were aristocratic precursors of modern postcards; in such works as Island of San Giorgio Maggiore, Francesco Guardi achieved both poetry and melancholy.