Calm (Liber Studiorum, part IX, plate 44), April 23, 1812, Etching, aquatint and mezzotint; third state of seven (Finberg), plate: 7 x 10 9/16 in. (17.8 x 26.8 cm), Prints, Turner distilled his ideas about landscape In 'Liber Studiorum' (Latin for Bo