"Owing to the mediation of cities, it became popularly possible to regard 'nature' as benign, ennobling and pure, and by extension to regard 'natural man' (take your pick of how 'natural') as so too. Opposed to this fictionalized purity, nobility and beneficence, cities, not being fictions, could be considered as seats of malignancy and -- obviously -- the enemies of nature. And once people begin looking at nature as if it were a nice big St. Bernard dog for the children, what could be more natural than the desire to bring this sentimental pet into the city too, so the city might get some nobility, purity and beneficence by association?
"There are dangers in sentimentalizing nature. Most sentimental ideas imply, at bottom, a deep if unacknowledged disrespect. It is no accident that we Americans, probably the world's champion sentimentalizers about nature, are at one and the same time probably the world's most voracious destroyers of wild and rural countryside."
-- from The Death and Life of Great American Cities by Jane Jacobs