`How many lives was it worth?'

The name above his study door -- in neatly painted letters, white on black -- was T. D. Weldon and, although the initials did not actually stand for "Territorial Decoration'', they might well have done. He was tall, robust in appearance and, oddly for an Oxford philosopher, had a somewhat military bearing. Rumour had it -- and the rumours turned out to be true -- that during the war he had been close to Sir Arthur Harris of Bomber Command. For some reason, he was known to everyone, including his pupils, as "Harry".

A confirmed bachelor (whatever that may mean), Harry lived alone in the Magdalen College rooms where he also taught. He had some kind of skin complaint -- his face was always red and his skin peeled -- and he smoked incessantly, using an ivory and silver cigarette holder reminiscent of a 1930s movie. In the evenings his door was always open and any undergraduate who did not find him too intimidating could drop in for a glass of whisky and an hour or so's talk. Yet, although he was, at one level, unusually friendly, he always kept his distance. Conversation never became personal.

I remember well the first time I met Harry. I had just arrived from North America, a part of the world where intellectual gurus -- Great Thinkers like George Santayana, Arnold Toynbee and Bertrand Russell -- were taken seriously, almost worshipped. In the course of working out my first assignment with him, I asked whether he had read Bertrand Russell's latest book, Why I Am Not a Christian. Harry took his cigarette holder out of his mouth, laughed and asked: "Who the hell wants to know why Bertie's not a Christian?" So that was that. End of gurus.

Harry had high standards. We subsequently discovered that in the 1930s and late 1940s he had been almost single-handedly responsible for turning Magdalen from a playground for the idle rich into an intellectually reputable institution. He did not suffer fools gladly. Asked why there were no white South African students in the college, he replied: "Solid ivory between the ears, dear boy.'' On another occasion, when a bunch of us who had been out with friends expressed surprise that some of them could not seem to grasp an elementary philosophical point, Harry merely muttered: "Oh, been out slumming, eh?" Like all the Oxford philosophers of his time, Harry Weldon in his teaching concentrated on problems of logic, language and epistemology. Clarity was the aim, not ultimate truth. Imagine our surprise, then, when one evening over whisky, after two years of logic-chopping tutorials, he suddenly asked: "How many lives is Cologne Cathedral worth?'' We could not answer the question. Neither, apparently, could he, even though it was one he must have asked himself during the war. Perhaps his inability to answer his own question explains why a few weeks later -- just before our finals in 1958 -- he took his own life. We none of us knew what to make of what had happened. I still do not. But we all knew that someone important had disappeared from our lives.

Anthony King is professor of government, Essex University. He is a member of the Nolan Committee, set up to investigate conduct in public life.