One of the most important relationships throughout history may well be humans' relationship to nature, i.e. our place within the natural order of things as well as our experience of the great outdoors. At various periods in time, artists have developed conventions for depicting this relationship; an early example in Western art being Giorgione’s The Tempest of 1506. In the characteristically playful compositions of the 17th-century Rococo style, nature often seems to come to life, at once seductive and mysterious, as evident in many of Fragonard’s flirtatious paintings. Perhaps the most iconic example of man's negotiation with the power of nature, Caspar David Friedrich’s Monk by the Sea, embodied the spirit of the 19th-century Romantics, who valued the individual’s subjective contemplation of nature as part of a personal, poetic experience. From Song Dynasty landscapes, in which human figures are dwarfed by enigmatic and wild natural settings, to the Impressionists' penchant for depicting outdoor leisure activities like boating or picnicking, what humans have defined as the boundary between "civilization" and "nature" has continually shifted, often in response to physical encroachments into the natural world, as in the case of the railroad and industrial expansion.