In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.

Passage: Caspar David Friedrich (5 September 1774 – 7 May 1840) was a 19th-century German Romantic landscape painter, generally considered the most important German artist of his generation. He is best known for his mid-period allegorical landscapes which typically feature contemplative figures silhouetted against night skies, morning mists, barren trees or Gothic or megalithic ruins. His primary interest as an artist was the contemplation of nature, and his often symbolic and anti-classical work seeks to convey a subjective, emotional response to the natural world. Friedrich's paintings characteristically set a human presence in diminished perspective amid expansive landscapes, reducing the figures to a scale that, according to the art historian Christopher John Murray, directs "the viewer's gaze towards their metaphysical dimension".Friedrich was born in the town of Greifswald on the Baltic Sea in what was at the time Swedish Pomerania. He studied in Copenhagen until 1798, before settling in Dresden. He came of age during a period when, across Europe, a growing disillusionment with materialistic society was giving rise to a new appreciation of spirituality. This shift in ideals was often expressed through a reevaluation of the natural world, as artists such as Friedrich, J. M. W. Turner and John Constable sought to depict nature as a "divine creation, to be set against the artifice of human civilization".Friedrich's work brought him renown early in his career, and contemporaries such as the French sculptor David d'Angers spoke of him as a man who had discovered "the tragedy of landscape". Nevertheless, his work fell from favour during his later years, and he died in obscurity. As Germany moved towards modernisation in the late 19th century, a new sense of urgency characterised its art, and Friedrich's contemplative depictions of stillness came to be seen as the products of a bygone age. The early 20th century brought a renewed appreciation of his work, beginning in 1906 with an exhibition of thirty-two of his paintings in Berlin. By the 1920s his paintings had been discovered by the Expressionists, and in the 1930s and early 1940s Surrealists and Existentialists frequently drew ideas from his work. The rise of Nazism in the early 1930s again saw a resurgence in Friedrich's popularity, but this was followed by a sharp decline as his paintings were, by association with the Nazi movement, interpreted as having a nationalistic aspect. It was not until the late 1970s that Friedrich regained his reputation as an icon of the German Romantic movement and a painter of international importance.
What is the last name of the person who is best known for his mid-period allegorical landscapes?