One of our favorite moments with Mayor Bloomberg occurred during the interview the mayor gave to a reporter of the Sun for our first issue. He was asked about the possibility of letting a private company build, operate, and own the Second Avenue subway line the city needs. “In this day and age, you would not … ” he started to say. Then he changed his thought and asserted that it was all up to Albany, in that the decision on the future of the subways that carry New Yorkers to and fro “has nothing to do with the city.” Then he said, “There’s not a chance in hell that Albany and the MTA would … ” But then he stopped again and simply demanded to know what the man from The New York Sun was smoking.

That was in April 2002, and we’re happy to say that in the years since then the mayor has taken up a certain kind of smoking. This is evident in his speech in Queens yesterday, sketching a vision for the city’s future. He unveiled a PLANNYC report that challenged New Yorkers to think about what the city is going to look like and need 25 years hence. By 2010, it said, “New York will have added a population the size of Salt Lake City.” By 2015 “our temperatures will have risen by half a degree.” It noted that by 2020 “40% of our power plants will be more than 50 years old.” It noted that by 2025 “more than 2 million people will live more than 10 minutes from a park.”

“By 2030,” his Plan-NYC report asked, “will you still love New York?” Certainly the private sector has been placing its bet. In the years since September 11, 2001, an enormous — and in many ways astonishing — boom has been underway in the city, as developers, real estate companies, and individuals take out permits to put up new buildings, large and small, that are already transforming the city’s skyline and its neighborhoods in all five boroughs. There is a great sense of the future here, where some buildings are selling for nearly $2 billion and others — as our David Lombino reported on Monday — are now reckoned to be worth as much as $3 billion for a single structure.

A share of the credit — hard to quantify, but certainly a significant share — goes to the mayor himself for establishing a management of the city’s government that has won broad confidence. What the mayor is now doing is moving to answer the question of whether the government can keep up with the dynamism and vision of the private sector. He is sketching what PLAN-NYC calls “ten goals for creating a sustainable city.” These include the creation of homes for almost “a million more New Yorkers,” improving travel times “by adding transit capacity for millions more residents, visitors, and workers,” and ensuring that New Yorkers “live within a 20-minute walk of a park.”

The plan also sets goals for maintaining the city — developing backup systems for its aging water network, reaching what it calls “a full state of good repair” of roads, subways and rails “for the first time in history,” and providing “cleaner, more reliable power for every New Yorker by upgrading our energy infrastructure.” The plan buys into the global warming fad more than we would like, but we’re not against clean air per se or against cleaning up contaminated land, two additional goals. The 10th goal, of opening 90% of the city’s waterways for recreation by reducing water pollution and “preserving our natural areas” strikes us as something that would radically improve the quality of life here; these columns have been campaigning for years for the return of swimming beaches on the East River.

There are plenty of questions looming over Mr. Bloomberg’s vision. Some are sketched by Edward Glaeser, in a piece that starts on page one. His essential point is that population and growth are good, that incentives to work and think here are as important as the hard infrastructure. A tax cut can be worth as much as a school or an apartment in helping New York attract and keep — in helping it compete for — the population that is at the root of our greatness. The debate over how to balance those issues can’t take place too soon. But it’s not too soon to say that if they mayor’s vision comes to pass, his legacy will be of historic proportions.