On Lewis Mumford's Urban Theories: For American urban theorist Lewis Mumford, human history has generally hinged on two opposing ideas, movement and settlement. While movement brought adventure, settlement brought security, and Mumford argued that cities have served as unique case studies for historians (and sociologists) who wish to examine these ideas in confined spaces. In 1961, he published The City in History, which sought to explicate how urban growth (through technology) has affected human culture over time, and thus, why movement and settlement ultimately define the human experience in cities. Perhaps Mumford captured the essence of a city best when he stated: "The city is a fact in nature, like a cave, a run of mackerel or an ant-heap. But it is also a conscious work of art, and it holds within its communal framework many simpler and more personal forms of art. The mind takes form in the city, and in turn, urban forms condition the mind." An ideal city, for Mumford, was one that struck a balance between nature and technology. In other words, a city that relied equally on its waterways and roadways for transporting goods, its parks and stadiums for entertaining and recreating residents, would invariably offer its planners the possibility for true organic growth.