Neil Smith, who died in September at age 58 of liver failure, brought a new dimension to geography by exploring the relationship between cities, the wider world and capitalism.
If we want to understand the economic system's workings, he argued, then we have to understand the spaces that make its existence possible. And if we want to live in a saner environment - natural and built - we need to revolutionise the ways in which it is produced.
As an undergraduate at St Andrews University in Scotland, Smith studied the way in which gentrification had become a global force in the shaping of cities. In addition to middle-class people seeking better lifestyles, he pointed to the rent gap, the difference between the rent a property earns currently and what it could earn if redeveloped for new inhabitants. When the gap is big enough, private capital is attracted by the financial potential, and restructuring follows.
By the time of his book The New Urban Frontier in 1996, Smith was an academic based in the US, and the argument had acquired a political aspect. It highlighted an effect akin to revenge as richer people returned from the suburbs to repossess inner-city areas, their interests combining with those of private capital to the detriment of the poorer people living there.
In the process, public-policy initiatives like zero-tolerance policing served to criminalise the marginalised and homeless.
Smith's arguments about gentrification were part of a larger examination of how capitalism shapes nature and geographical space, whether land, sea, air or buildings.
This approach to geography attracted scholars in such fields as anthropology and sociology to the study of space and place.
Neil's view as to why pioneering work such as his came comparatively late to geography in the US is in large part because that suited the rise of American-led, capitalist liberalism.