In chess, I also had the first direct experience of him as a thinker. As he analysed for my benefit the classic great games, or the more recent contests of the world's best players, I was filled with admiration for the workings of his brilliant mind, its immediate grasp of the most complex problems, its analytical power, the flashes of insight. When he confronted the board his features became fixed in utter concentration, his gaze became sharp and penetrating. Logic and intuition, the instruments with which he'd pursued for two decades the most ambitious intellectual dream, sparkled in his deep-set blue eyes.

Once, I asked him why he had never entered official competition.

He shook his head. 'Why should I strive to become a mediocre professional when I can bask in my status as an exceptional amateur?' he said. 'Besides, most favoured of nephews, every life should progress according to its basic axioms and chess wasn't among mine – only mathematics.'

The first time I ventured to ask him again about his research (after the extensive account of his life he had given me, we'd never again mentioned anything mathematicaL both of us apparently preferring to let our sleeping dogs lie) he immediately dismissed the matter.

'Let bygones be bygones and tell me what you see on the chessboard. It's a recent game between Petrosian and Spassky, a Sicilian Defence. White takes Knight to f4…'

More oblique attempts didn't work either. Uncle Petros would not be coaxed into another mathematical discussion – period. Whenever I attempted a direct mention it would always be: 'Let's stick to chess, shall we?'

His refusals, however, didn't make me give up.

My wish to draw him once again to the subject of his life's work was not fired by mere curiosity. Although it was a long time since I had any news of my old friend Sammy Epstein (last time I'd heard of him he was an assistant professor in California), I couldn't forget his explanation of Uncle Petros giving up his research. In fact, I'd come to invest it with great existential significance. The development of my own affair with mathematics had taught me an important lesson: one should be brutally honest with oneself about weaknesses, acknowledge them with courage and chart further course accordingly. For myself I had done this, but had Uncle Petros?

These were the facts: a) From an early age he had chosen to invest all his energy and time in an incredibly, but most probably not impossibly, difficult problem, a decision which I still continued to regard as basically noble; b) As might reasonably have been expected (by others, if not by himself) he had not achieved his goal; c) He had blamed his failure on the incompleteness of mathematics, deeming Goldbach's Conjecture unprovable.

Of this much I was now certain: the validity of his excuse had to be judged by the strict standards of the trade and, according to these, I accepted Sammy Epstein's opinion as final – a final verdict of unprovability a la Kurt Gödel is just not an acceptable conclusion of the attempt to prove a mathematical statement. My old friend's explanation was much closer to the point. It wasn't because of his 'bad luck' Uncle Petros hadn't managed to achieve his dream. The appeal to the Incompleteness Theorem was indeed a sophisticated form of 'sour grapes', meant only to shelter him from the truth.

With the passing of the years, I had learned to recognize the profound sadness that pervaded my uncle's life. His absorption in gardening, his kindly smiles or his brilliance as a chess player couldn't disguise the fact that he was a broken man. And the closer to him I got, the more I realized that the reason for his condition lay in his profound insincerity. Uncle Petros had lied to himself about the most crucial event in his life and this lie had become a cancerous growth that stifled his essence, eating away at the very roots of his psyche. His sin, indeed, had been Pride. And the pride was still there, nowhere more apparent than in his inability to come face to face with himself.

I've never been a religious man, yet I believe there is great underlying wisdom in the ritual of Absolution: Petros Papachristos, like every human being, deserved to end his life unburdened of unnecessary suffering. In his case, however, this had the necessary prerequisite of his admitting the mea culpa of his failure.

The context here not being religious, a priest could not do the job.

The only person fit to absolve Uncle Petros was I myself, for only I had understood the essence of his transgression. (The pride inherent in my own assumption I did not realize until it was too late.) But how could I absolve him if he did not first confess? And how could I lead him to confession unless we started once again to talk mathematics, a thing he persistently refused to do?

In 1971, I found unexpected assistance in my task.

The military dictatorship that then ruled the country, in a campaign to appear as a benevolent patron of culture and science, proposed to award a 'Gold Medal of Excellence' to a number of rather obscure Greek scholars who had distinguished themselves abroad. The list was short, since most of the prospective honourees, forewarned of the impending distinction, had hastened to exclude themselves; but topmost in it was 'the great mathematician of international fame, Professor Petros Papachristos'.

My father and Uncle Anargyros, in a totally uncharacteristic frenzy of democratic passion, strove to convince him to turn down this dubious honour. Talk of 'that old fool becoming the junta's lackey', 'giving the colonels an alibi', etc., filled our business offices and family homes. At moments of greater honesty the two younger brothers (both old men, by now) confessed to a less noble motive: the traditional reluctance of the businessman to be too closely identified with one political faction for fear of what will happen when another comes to power. Yet I, an experienced Papachristos family observer, could also discern a strong need for them to be proved right in their negative evaluation of his life, also tinged with an element of envy. Father's and Uncle Anargyros' world-view had always been founded on the simple premise that Uncle Petros was bad and they good, a black-and-white cosmology that distinguished between the grasshoppers and the ants, the dilettantes and 'responsible men'. It didn't sit at all well with them that the country's official government, Junta or no Junta, should honour 'one of life's failures', when the only rewards they ever got for their labours (labours, mind you, that also put food on his table) were financial.

I, however, took a different position. Beyond my belief that Uncle Petros deserved the honour (he did, after all, rate some recognition of his life's work, even if it came from the colonels) I had an ulterior motive. So I went to Ekali and, exercising to the full my influence as 'most favoured of nephews', convinced him to overcome his brothers' hypocritical appeals to democratic duty as well as his own misgivings and accept his Gold Medal of Excellence.

The award ceremony – that 'ultimate familial disgrace', according to Uncle Anargyros the late-blooming radical – was held in the main auditorium of the University of Athens. The Rector of the School of Physics and Mathematics, in his ceremonial robes, gave a short lecture on Uncle Petros' contribution to science. Predictably enough he referred almost exclusively to the Papachristos Method for the Solution of Differential Equations, which he lauded with elaborate rhetorical effusions. Still, I was agreeably surprised to hear him also make passing reference to Hardy and Littlewood and their 'appealing to our great fellow-countryman for assistance with their most difficult problems'. While all this was being propounded I stole side-glances at Uncle Petros and saw him blushing red with shame again and again, all the time retreating further into the throne-like, gilded armchair where they had him installed. The Prime Minister (the arch-dictator) then bestowed the Gold Medal of Excellence and afterwards there was a short reception, during which my poor uncle was required to pose for photographs with all the top brass of the Junta. (I have to confess that at this stage of the ceremony I feit a slight dose of guilt about the defining role I had played in his acceptance of the honour.)