With the passing this week of Jane Jacobs, New Yorkers have lost a voice of reason in urban planning. With the publication of “The Death and Life of Great American Cities,” Jacobs struck a blow against the forces that favored grand scale and modernist aesthetics over livability in urban life. While her zeal led her sometimes into other sorts of planning errors, her book, in print since its release 45 years ago, has never been more relevant today.

Jacobs’ achievement is noteworthy chiefly because she was writing in 1961, before some of the worst planning excesses of the 1960s and 1970s. By that time, cars were already transforming the urban landscape. Concrete block housing projects were multiplying. The full effects of these “seeds” and others had yet to blossom forth. Many people in the late 1950s and early 1960s – indeed, some today – failed to see that such housing projects were doomed because they didn’t account for the humanity of the people who would inhabit them.

Jacobs did see. “Seeing” was the hallmark of her work, and she believed it should undergird all planning theory. Her eyes, focused on the city around her, became her chief weapons against the prevailing urge toward constructing what she derogatorily called “Radiant Garden City Beautiful” projects. Such development combined the worst excesses of Le Corbusier’s Radiant City of sterile high-rises set off from their neighborhoods, Ebenezer Howard’s Garden City of neighborhoods set off from their cities, and Daniel Burnham’s City Beautiful with its monumental civic structures hulking over everything.

The failure of other planners to observe closely the life of real cities lay at the heart of her criticism. “Cities are an immense laboratory of trial and error, failure and success, in city building and city design,” she wrote in the introduction to “Death and Life.” “This is the laboratory in which city planning should have been learning and forming and testing its theories. Instead the practitioners and teachers of this discipline (if such it can be called) have ignored the study of success and failure in real life, have been incurious about the reasons for unexpected success, and are guided instead by principles derived from the behavior and appearance of towns, suburbs, tuberculosis sanatoria, fairs, and imaginary dream cities – from anything but cities themselves.”

She did not make the same mistake. She observed carefully. “Death and Life” includes three chapters of observations just on sidewalks. Such observation led her to see how functional sidewalks could discourage crime, facilitate healthy social contact, and aid in child-rearing. For example, she came to understand that constant surveillance carried out unwittingly was a key ingredient for street safety. In the act of indulging a human predilection for “people-watching,” neighbors would naturally spot trouble brewing on the street and be able to intervene. Shops and restaurants serve not just an economic purpose but a safety function as well, by attracting the foot traffic that in turn captures the intermittent attention of office workers or shopkeepers or stay-at-home parents (housewives, in 1961).

“This last point,” she wrote, “that the sight of people attracts still other people, is something that city planners and city architectural designers seem to find incomprehensible. They operate on the premise that city people seek the sight of emptiness, obvious order and quiet. Nothing could be less true. People’s love of watching activity and other people is constantly evident in cities everywhere.” Jacobs turned her weakness, a lack of formal planning credentials, into her strength. Her planning education consisted of living in the city.

Perhaps as a result, she was able to see right through some of the common complaints of urban planners, complaints that echo to this day. She was no great fan of the car, but she understood that it was not the reason for many of the ills afflicting cities. “Automobiles are often conveniently tagged as the villains responsible for the ills of cities and the disappointments and futilities of city planning. But the destructive effects of automobiles are much less a cause than a symptom of our incompetence at city building. Of course planners … are at a loss to make automobiles and cities compatible with one another. They do not know what to do with automobiles in cities because they do not know how to plan for workable and vital cities anyhow – with or without automobiles.”

Jacobs was of the left-wing (she and her husband eventually moved to Canada so that her sons could escape the Vietnam draft), but she was keenly aware of the inability of central planners, or more money, to change human nature or to reshape cities for the better.

“There is,” she wrote, “a wistful myth that if only we had enough money to spend … we could wipe out all the slums in ten years, reverse decay in the great, dull, gray belts that were yesterday’s … suburbs, anchor the wandering middle class and its wandering tax money, and perhaps even solve the traffic problem. But look what we have built with the first several billions. Low-income projects that become worse centers of delinquency, vandalism and general social hopelessness than the slums they were supposed to replace….”

Hers was a liberalism of smallness, not of Lyndon Johnson’s bigness. This could lead her into errors of her own, as when she bemoaned the conversion by a private landlord of several buildings on her block into one larger luxury apartment building. Even such private development, she feared, could damage a block by interfering with the delicate balance of the neighborhood. Left unanswered in her book is the question of how much of that disruption was caused by such development or whether the concomitant increase in two earner households had a more profound effect on many residential communities. Housewives, after all, constituted much of the cast of the “ballet” Jacobs saw unfolding on her block and in her local park and lending life to both.

The bulk of “Death and Life,” however, is devoted to exposing the dangers of the kind of big project that only gets built with a nod and a lot of cash from government planners. As New Yorkers witness a new generation of such developments unfolding before them, Jacobs bears careful re-reading. Her enduring legacy will be her call to think about how such projects fit into the cities around them and her reminder that central urban planners have rarely been smarter than the organic cities they have tried to reshape.