Peter Drucker was a revolutionary thinker - and the world beat a path to his door.
Stepping through it, however, one would hardly have guessed at his huge stature as a management guru.
When I went to see him eight years ago, he was 87. His wife, one year older, had just started a new business.
Peter Drucker died on 11 November, aged 95
He had little help and no secretary as far as I could see. Negotiations to visit him were conducted by fax; he personally scribbled meticulous details, times dates, recommended hotels and driving instructions on the bottom of your letter and faxed it back.
He lived in a rather unassuming house in the suburbs under the foothills on the edge of Los Angeles where he had taught middle managers for years at Claremont Graduate School, which named its business school after him. Though rather deaf, his bookshelves there were full of music on 33rpm vinyl records.
Yet managers from across the world fell over one another to learn from his extraordinary formative wisdom: not a word used in connection with many business commentators. He went on and on, shaping and reshaping his ideas well into his 90s, and he was 95 when he died in November.
One of the difficulties of interviewing Professor Drucker was how to decide what to talk about. He had defined so many circumstances of 20th century business, including the seminal thoughts on the idea of the corporation based on unique access to Alfred P Sloan's General Motors in the 1940s. He had ideas about many more.
In particular Peter Drucker was not carried away by computers. They have yet to make their impact on the way organisations are run, he said, baldly.
"Everyone knows how to run a computer," he told me. "But managers don't yet know what to do with the information. The most important information is not what goes on inside the organisation but what goes on outside, and that information is not available and in most cases doesn't exist."
Peter Drucker predicted health service management problems
And then, following on from this, Peter Drucker's compelling self analysis. "You say what do I contribute to my clients? My main contribution is that I am always looking on the outside and they don't."
This resonant lesson of business life, remember, from an 87-year-old.
Despite his wariness, Peter Drucker turns out to be the inspiration behind the personal computer. According to Alan Kay of the Xerox PARC research centre in Silicon Valley California, it was the Professor's identification of the coming importance of the knowledge economy (a Drucker coinage) that inspired him to do the spadework on what became the desktop PC.
I mentioned to Peter Drucker a recent encounter I had had with the architect of the McKinsey management consultancy, Marvin Bower: effectively the man who raised consulting to professional status, single-handedly.
In his only broadcast interview, I had recently asked Marvin Bower what he most regretted about his 60 years of experience in American business. His answer : "The continued prevalence of command and control."
When I put the same question to Professor Drucker, he nodded. "I heartily agree with my friend Marvin Bower," he said.
Closer to home
After the recording was over, we took him to lunch at his local Italian restaurant, and the insights kept coming.
Professor Drucker was in at the start of the welfare state here in Britain. As a friend of Sir William Beveridge, he had identified the weakness of the National Health Service from the very beginning, he said.
The inspiration for the PC remains suspicious of their impact
Doctors, once won over to the NHS idea, provided first class service. But higher level administration was flawed from the start, because of the way that hospital administration did not match local government boundaries.
It was a failure from which Britain was still suffering, 50 years after Peter Drucker had helped Beveridge formulate the plans, and it still is.
Talking more about computerisation, Drucker mentioned the stock control system used at Marks and Spencer in the 1930s.
"Simon Marks took the ticket on the merchandise and instead of it being one piece of paper it became two pieces. And whenever something was sold the checkout woman tore off the lower half and put it into a cigar box. Cigar boxes were hi-tech in 1930.
"And twice a day a trainee phoned the numbers through to Baker Street and automatically the order went to the supplier."
And how did he know this detail of 1930s British business life ? Oh, Peter Drucker's wife Doris was the very first M&S market researcher, he said.
Modest about management
Peter Drucker never won a Nobel Prize for anything because academics are snooty about management.
But he shaped the way we work in the 20th century more than anyone else, and his ideas still resonate. In later life, he spent much of his time thinking about non-profit institutions.
He called the Salvation Army "the most effective organisation in America", because of the way it delivered what it set out to do, decade after decade.
You might say the same of Professor Drucker. He will be missed.
Work in Progress is the title of this new exploration of the big trends upheaving the world of work as we steam further into the twenty-first century; and it is a work in progress, influenced and defined by my encounters as I report on trends in business and organisations all over the world.