I've been interested in cities for as long as I can remember. My childhood is marked by Lego metropolises on the living room floor, streetscapes doodled in schoolbooks and early Saturday mornings playing SimCity for hours on end. So it only made sense that, when I was fourteen, on a beautiful summer day spent wandering Vancouver's streets, my uncle turned to me and insisted that I read Jane Jacobs.

"Sure," I mumbled in a teenagerly way and we continued walking. He proceeded to tell me about a Marxist-Leninist bookstore on Hastings Street that had a great urban-issues section. "You should go there sometime," he added.

Later that year, sitting under my family's Christmas tree, I ripped opened a present from my uncle, revealing a bold mustard-coloured paperback. The title was stamped in bold capital letters: The Death and Life of Great American Cities. Below it was a blurb from the New York Times Book Review: "Perhaps the most influential single work in the history of town planning... a work of literature."

It wasn't until the following spring that I actually got around to reading Jane Jacobs' 1961 classic, a book so widely read that it has never gone out of print. It opened my eyes. It confirmed what I had already begun to suspect about cities, about the way they worked, looked and felt, about their cultures and economies. Looking around the Calgary of my youth, I saw how suburban planning had deprived the city of a public sphere. When I moved to Montreal, I was ecstatic to find exactly the opposite: a city whose human spirit was alive and visible in its streets, businesses and buildings. The seed of my interest in cities was planted a long time ago; Death and Life made it grow into something robust.

This book is an attack on current city planning and rebuilding. It is also, and mostly, an attempt to introduce new principles of city planning and rebuilding, different and even opposite from those now taught in everything from schools of architecture and planning to the Sunday supplements and women's magazines.

So reads the first line of Death and Life­, a stinging slap in the face of almost every established urban planner, architect and bureaucrat in North America at the time. Here was an outsider-a woman, a writer, a mother-with no formal training in planning who had taken it upon herself to obliterate more than a century of conventional thinking about cities. In the 458 pages that followed her blistering introduction, Jacobs did more to reshape our vision of the modern city than almost any other thinker in recent history.

What was so radical about Jacobs' vision, at the time, was her insistence upon seeing the city as an organism; one that evolves naturally over time and is as complex and dynamic as the human beings that live in it. To put it very simply, she advocated a ground-up approach to urban planning and urban governance. Plan for how the city actually works, she told us, instead of determining how it ought to work.

Jacobs' ideas are nuanced and complex, but the essence of her philosophy has been expertly synthesized by the Project for Public Spaces (PPS), a non-profit organization dedicated to creating and sustaining community-building public spaces. The PPS breaks down her arguments into easily understandable components:

• Cities are ecosystems in which every element, from sidewalks to neighbourhoods to economies, "functions together synergistically."
• Mixed-use development allows for the diversity of buildings, residences and businesses required to create vibrant, inclusive and dynamic neighbourhoods.
• · High density is essential to achieving this dynamism. Density was long a bugaboo of civic leaders, who associated it with disease, squalour and vice. But Jacobs effectively demonstrated how density-when it takes the proper form-can create safe, tightly knit and economically successful communities
• Communities are the building blocks of social and economic progress. Jacobs stressed the need for bottom-up development and support for small businesses and grassroots entrepreneurs.

Jacobs died last month in Toronto, her adopted home of thirty-eight years, where she had become a well-known and well-respected activist leader and a voice of reason. Her influence, however, is felt far and wide. Since the publication of Death and Life, Jacobs' ideas revolutionized civic life. She helped to unleash a revolt against the Modernist city planning-highways, slum clearance, superblocks-that decimated North American cities in the 1950s, 1960s and 1970s. The revolt led directly to New Urbanism, a philosophy of urban planning that drew heavily from Jacobs' ideas.

But Jacobs' legacy is controversial. She is equally appealing to the grassroots left and the neoliberal right, which has led to her co-option by both sides of the ideological spectrum (despite Jacobs' adamant refusal to be pinned to any single system of belief). This was especially evident after her death, when plaudits came showering in from every direction. Her ideas on urban design were widely lauded in the mainstream media, with glowing obituaries published in the Globe and Mail, the Guardian, the New York Times and countless other papers. Many of the more astute obituaries reflected, as Howard Husock did in City Journal, on Jacobs' "faith in cities and people to work out their problems in original ways, ways which would create new jobs, new wealth, and, ultimately, lead to new problems that people would eventually solve as well."

But there was criticism, too. New York Times architecture critic Nicolai Ouroussoff all but dismissed Jacob's urban vision as quaint and nostalgic. Of course, Ouroussoff (whose column, ironically, is titled "Streetwise") is unabashedly enthralled with-and writes about little other than-an elite group of "starchitects" whose designs are often conceptually brilliant but ultimately dysfunctional and poorly integrated into the city.

I wanted to get a sense of what Jacobs means to us today, forty-five years after the publication of Death and Life. Eschewing the usual expert opinions-the ones we've been hearing so much since Jacobs' death-I decided to talk to someone of whom she would have approved; a fellow amateur urbanist, Steve Boland.

Boland publishes San Francisco Cityscape, a city-issues blog that draws heavily from Jacobs' urban philosophy. "Reading Death and Life was a definite turning point," he tells me. "I've since read loads of other writers, but what really got me about Jane was the talented amateur quality [of her work]. She was an observer. It gives you this idea, if you're a young person who's just sort of getting into this, that 'I can do this too.' You start observing your own city. It deepens your understanding and at the same time it deepens your interest."

The tug-of-war that has occurred over Jacobs' legacy amuses Boland. "Everybody wants a piece of Jane," he says, laughing. "What happens a lot is that people are very selective in their interpretations of her, which is why you can have people who arrive at such radically different conclusions from her books." Even though New Urbanism is closely identified with her ideas, Jacobs criticized it for creating the kind of overly regulated, master-planned developments she lambasted in Death and Life. But she was still sympathetic to most of New Urbanism's goals-after all, a large part of the New Urbanism movement focuses on piecemeal urban infill and not the wholly packaged, Disneyesque subdivisions that garner so much attention. So when prominent libertarians cite Jacobs in their attacks on smart growth, as Leonard Gilroy did in a recent Washington Post editorial, their arguments fall flat. "There is a libertarian nugget in Jane's work," says Boland. "She was railing against big government, essentially. She was talking about a market, a lot of interactions between ordinary people. But where the libertarians get in trouble is when they take that concept and ignore anything else, all the humanizing qualities of her argument."

Some observers have suggested that Jacobs is no longer relevant, or is only relevant to inner cities that have now (much to Jacobs' chagrin) been gentrified. But her influence is widely felt in almost every aspect of urban life. Adaptive reuse of old buildings, the role of streets and parks as public spaces, the cultural import of postering, public markets as economic incubators, safety on the streets and public participation in local governance; these kinds of things play a vital role in the well-being of the city but are invisible to the untrained eye-or to the blind eye. "If you live in a world of pure theory, which leads to ideology, which leads to you excluding any evidence that doesn't support your belief structure, then you stop observing," insists Boland. "You lose your common-sense approach to things. I don't think Jane ever lost that clear eye. She wasn't burdened by ideology."

That clear-eyed approach is something I admire and something I have always strived to incorporate into whatever I do. In university, working towards a degree in Canadian Studies and History, I looked at things through an urban lens. I tried to see how cities shape our society and how we shape our cities.

I still have the copy of Death and Life that my uncle gave to me when I was fifteen. Looking at it in front of me, its edges slightly dog-eared, I remember what it did for me the most-it taught me to see the city.

Christopher DeWolf wanders our streets as Maisonneuve's urban affairs critic. His column appears every two weeks. Read more columns by Christopher DeWolf.