In the first sentence of The Death and Life of Great American Cities, Jane Jacobs's 1961 manifesto on how to save urban centers in decline, the author says, "This book is an attack on current city planning and rebuilding." The tone only grows more combative from there.

Given how often Jacobs is cast merely as a foil to Robert Moses—the dogged organizer who battled to preserve her beloved West Village—it's tempting to view her as somewhat quaint or reactionary. Her writing is emphatically neither of these things. Within 25 pages of Death and Life, she has blithely dismissed 100-plus years of planning theory. Far from advocating neighborhoods as cute, tightly knit townships, she argues vehemently for privacy and the comfortable anonymity that cities afford. While she doesn't exactly love large-scale development projects, Jacobs clamors for cities to pack themselves with more buildings, more streets, more people…even more factories.

"A lot of people assume that Jacobs is a romantic who positioned herself against hardheaded, practical people," says Kent Barwick, president of the Municipal Art Society of New York (MAS), "but she is pretty tough-minded." (The MAS recently created an exhibition on Jacobs's ideas, viewable starting September 25.) This is the side of Jacobs that's often overlooked. She didn't just argue against things; she invited cities to grow aggressively and embrace their unique assets.

Specifically, she outlined four qualities that any city neighborhood must have in order to be healthy and desirable to residents. We give you the cocktail-party version:

1. Mixed primary uses
2. Short blocks
3. Aged buildings
4. High density of residents