Those who have already, teach.

To a loyal cadre of Manhattan real estate executives, Lawrence Fiedler is guru par excellence. His disciples are scattered throughout the trade and are featured, as often as not, in the pages of this newspaper.

The guru in question? He's an adjunct professor at New York University's Real Estate Institute.

Since 1978, he's taught scores of rising stars who've gone on to work in the New York City real estate market. A remarkably high number of them stick around Manhattan.

"His classe are really fun. Larry enjoys debating with his students," said Simon Ziff, president of Ackman-Ziff and a former student.

"He's really a friend. The man uses teaching as his life platform." Ziff credited Fiedler for "directing people to my firm."

Simon is one of six Ackman-Ziff employees who've earned degrees from the NYU Real Estate Institute and taken a Fiedler course in the process. There are many more like Ziff in the industry.

When Fiedler discusses his business, he rarely uses jargon or technical terms. There is nothing narrow-minded about his approach.

His concept of real estate markets is holistic, in the sense that no market is an island. He can explain the dynamics of a recession along with the psychology that underpins a bull market.

Though he is a teacher, his approach is hardly pedantic. He keeps his subject conversational rather than preachy. The man likes to say what he thinks.

It wasn't always that way. For a period in the 1960's, Fiedler was questing for a calling.

"Between the time I was twenty and the time I was thirty, I jumped out of the law and into politics," said Fiedler, laughing.

Fiedler couldn't seem to work in any capacity for longer than 18 months. He repeatedly jumped ship through the seventies. Stints as a politician -- assistant to a New York City mayor -- and some entrepreneurial work filled this period of time. He even earned a law degree.

Sitting in his midtown office on a recent Friday morning, Fiedler is an imposing figure. He doesn't appear to be the type of man who was ever torn between much of anything. Here is a man who likes to talk about what he knows; people just happen that they pay him to do it. At times, he sounds downright roguish as he recalls his career.

Since 1978, he has taught real estate at New York University in some capacity. In the early 1970's, Fiedler cut his teeth on a real estate deal. He was a banker at the time, and the deal involved a large apartment complex being built in Miami.

"It was a wonderful world back then," said Fiedler wistfully. What follows is why:

"If you had enough leverage on a transaction, you could raise the equity capital from investors who, if they were in a high enough tax bracket, never really had to put up any hard cash at all. As a matter of fact, the more debt you piled on, the safer the deal was for the investors," said Fiedler, adding that "it was an anomaly."

He opened his firm -- "at my kitchen table" -- in 1973. By 1986, he had 12,000 SF of space on Park Avenue with 40 employees in New York and 25 people in Denver.

He managed and acquired several properties during this time. The largest deals he did were in the $25 million range and these included quite a few garden apartment transactions in Florida and Texas. At the time, the core of his cash flow came from syndication fees, that is up until 1986, the year of the Tax Reform Act.

"So I lost twenty five, fifty million dollars. So what? It was on paper, anyway," said Fiedler, shrugging.

"Larry has his own loyal following. He is a bright and interesting guy with tremendous insight," said Kenneth Patton, associate dean of the Real Estate Institute. "We think the world of Larry."

Another colleague weighed in less artfully on Fiedler.

"What was my first impression of Fiedler? Bombastic," said Garrett Theelander, vice president of Dresner Bank and a fellow teacher at NYU..

"He's opinionated. He can be overwhelming. You have to tell him to shut up every now and then. But he really is the anchor of the program."

Theelander added that despite the fact that Fiedler is a "rotund loudmouth", he has "the utmost respect for him."

In the course of an hour, Fiedler analyzed the retail market in New York City ("nothing is recession-proof -- it is ridiculous to say so"), the nature of this booming market ("New York's market can shut down on a piece of bad news. Bang!"), and the Greater Fool Theory. His animated take on just about any topic is contagious, spurring the listener to cue him on to any number of other topics. These he can exhaust.

"The market is a reflection of human nature. When things are going great and you've never seen a bad real estate market, you assume it will go on forever. Optimism drives the market higher and higher. But the minute something bad happens, you become negative, more of a bear. This applies not only to the stock market but also to the real estate market," said Fiedler.

But can the real estate market continue to climb?

"Newton's Law, remember. Everything that goes up must come down," he said.

Fiedler also pointed out that a reduction in demand now will result in an overbuilt situation. He labeled this market "tremendously volatile," particularly on the commercial side.

"Five years from today, if the market is 75 percent occupied rather than, say, 80 percent, you'll see those rents drop down 30 to 40 percent," said Fiedler.

When he talks about rents rising and falling, the discussion isn't necessarily academic. Fiedler's interests are at stake. "We own a building between 57th and 58th street on Madison," said Fiedler, who is also president of JRM Development Enterprises, Inc.

It helps that Fiedler is involved with the industry on another level beyond academia. And his students benefit from this immensely.

"He implements one of the most practical approaches to teaching real estate," said Miguel Battista, a former student now living in London.

"He brings the stock and bond markets, the Fed's actions and exposure to industry executives into the study of real estate," said Battista.

Fiedler can reel off the names of many high-profile real estate executives whom he has met or knows well. He's got strong opinions about them. Of one unnamed executive, Fiedler has nothing but good things to say. When another name comes up, he responds scathingly. There is a cantankerous edge to Fiedler.

There aren't many things that Fiedler doesn't have a strong opinion about, after all.

"The real estate community has very strongly backed the real estate institute, mainly the New York real estate institute. The institute is a product of this community," he said.

It's fitting that the real estate community is to a large degree a product of the institute -- and Professor Fiedler.