(FORTUNE Magazine) – "WE ARE PETER AND GEOFF," SAID PETER DRUCKER, AND he wasn't asking me, he was telling me. I was about to introduce him at a management conference. He had been through it all countless times before and understood that I would never presume to call a 91-year-old man by his first name, especially not a great man whom I revered. But in conversation we would be on a first-name basis, he insisted. I'm not sure I ever did bring myself to call him Peter. I think I just avoided calling him anything.

When it came to Drucker, who died Nov. 11 at the age of 95, the world suffered from Great Man Syndrome, but he did not. He was justly lauded and adored as the greatest management thinker and writer of all time, but he wasn't interested in any of that. Whenever I encountered him, as I did into his 90s, I found a man who was smiling, cheerful, and funny. His hearing and sight were going fast, yet he wasn't old. I don't know how you get to be ninetysomething without growing world-weary, but he did it.

That means he was guaranteed fun to talk to on any subject. As it happened, we had something in common, since Drucker had been a journalist as a young man in Germany. He thus had license to be scathing on the topic, as he was also when it came to management consultants who are low on substance but high on marketing pizzazz, of which there are always a few. He had a brilliant line that skewered both groups: "The reason reporters call these people gurus is that they're not sure how to spell 'charlatan.'"

Drucker simply didn't care about the conventional view on any management topic, since he had thought them all through and knew where he stood. Yet I was still surprised by the vehemence with which he disdained the modern vogue for exalting leadership, as distinct from paltry old management. It infuriated him, though he was too polite to say so unless you asked him about it, which I did. His reasoning was extremely simple: "The three greatest leaders of the 20th century were Hitler, Stalin, and Mao. If that's leadership, I want no part of it."

There were many things Drucker wanted no part of. Big universities, for instance. He scorned them all to remain at tiny Claremont College--payback, perhaps, for the scorn they'd heaped on him early in his career. Economists dismissed his work as cheap sociology. Sociologists had no use for business. And Drucker was dismissive of them all. "No economists were interested in organizations," he explained in a 2001 interview with my colleague, Jerry Useem. The field "was based on the asinine assumption that organizations act like individuals. They don't." Here, Drucker had sensed a huge opportunity. Like any great entrepreneur--"somebody who creates something new," as he once defined the term--he was raiding these older disciplines to create one that didn't yet exist. Physics sprang from Newton, economics from Adam Smith. And Peter Drucker became the undisputed father of management--the discipline devoted to the study of organizations.

Drucker's career was so productive for so long--his first U.S. book was in 1939, his last Harvard Business Review article in 2004--that he pretty well ran the table on management topics. James Thurber once told how disconcerting it was for him as a humorist to light on an excellent subject, only to find, as he often did, that Robert Benchley had written a shorter and funnier piece about it 20 years before. The situation for us management writers is far worse. Think of virtually any hot topic in business today other than the Internet--global competition, executive pay, the rise of information and services--and odds are that Drucker wrote about it with extraordinary perception, probably before 1970. It's one thing to talk about the rise of the "knowledge worker." It's another thing to predict it in 1959.

I once mentioned a particular debt to him, noting that in writing a piece for FORTUNE's 70th-anniversary issue I had relied on his work about the evolution of management. He reminded me that he had been the editor of FORTUNE's tenth-anniversary issue. Henry Luce had spotted him--Drucker was just 30--and asked him to oversee the issue on short notice. It was apparently a rude shock. "We had two months to go," Drucker recalled. "Absolutely nothing had been done." No wonder he liked to make fun of journalists.

When Drucker and I--excuse me, Peter and I--were done chatting on that stage, I stepped forward to introduce him. He was to my left, seated, since he couldn't stand up for the hour his talk would last. Nor was his hearing good enough to understand anything I was saying at the podium. He would begin speaking when he saw me leave the stage and heard the applause for him.

I reminded the audience that on each of the two previous mornings I had introduced a Nobel Prize winner in economics. Now it was time for Drucker. Of course there isn't any Nobel Prize in management thinking and writing. But as I explained on that morning, it's probably just as well--because if there were, it would have been won every year by the same man.