I saw my first Afro hairstyle on Telegraph Avenue in Berkeley in May 1968. At this remove, it is hard to summon up, let alone describe, the shock of that sight. I had not realised human hair could be made to assume such a shape, and for a moment I thought the young man - T-shirt, cut-offs, sneakers, mirror sunglasses - must be wearing an adapted Guardsman's bearskin: after all, the Age of Aquarius was also the Age of Gallimaufry. But no, it was Hair! all right.

Did I realise what a momentous time I had chosen to go to California? Even to say I chose to go there is an overstatement. The previous winter, on unpaid leave from my lowly job with Aer Lingus, I had drifted first to Holland and then to America where, at the invitation of some musician friends, I found myself pretending to sing and play with an Irish folk group on St Patrick's Day in an Irish bar in San Francisco.

One of the surprises of middle age is that the sins of one's youth are still a cause for blushes. I was an unlikely balladeer; I could hardly manage the three-chord trick on the guitar, and had a less than firm grasp of the words of the songs we performed. It hardly mattered; we were Irish, the genuine article. The following night I went to a party in the city, met some students from across the Bay in Berkeley, made friends, fell in love, and in May I was back in California, without a guitar this time.

Berkeley the town, as distinct from the iconic image it has become, was a dull little place even then; what lent it colour, energy, excitement - romance! - was the political ferment bubbling away everywhere one looked. Authority was being challenged wherever it risked putting its head above the barricades. There were protest marches, sit-ins, love-ins - I missed out on those - and everywhere, always, endlessly, the campaign against the war in Vietnam. All this was fascinating, but for me, a 23-year-old airline clerk from Ireland, what was truly captivating was what one might call the tone of life on this tawny shore of the Pacific, the stopping-place of last best hope for the westward-driving pioneers of the 19th century. Here I found a new version of what it was to be alive. Suddenly I realised that there were other people in the world who thought as I did, who had the same hopes, fears, angers, ambitions. No one in Berkeley - at least, no one I consorted with - thought art was for sissies, or that a pensionable job was the highest desideratum, or that sex was shameful, or that the middle-aged had a monopoly on wisdom. As always, it is the "small" things I remember best. I can recall with eerie clarity the first time I saw the vegetable counter in the local supermarket. I can still taste the first avocado pear I ate. And as for hash brownies . . . after a few of those it was impossible not to love Alice B. Toklas.

I see myself one morning sitting on the living room floor in a house in Parker Street listening to a record of Alfred Deller singing Purcell; the counter-tenor's voice was as much of a surprise as the sight of that Afro on Telegraph Avenue or the taste of that tender-green avocado. "Sound the trumpet!" Deller sang, and I seemed to hear in this exquisite sound the very clarion call of a future I had hardly thought possible before I came to California.

However, lest we forget . . . 1968 may have been the year when thousands of us fifty-somethings found ourselves spiritually, but it was also one of the most appalling 12 months that the century has known outside wartime. Let us refresh our memories, if "refreshing" is a fit word to apply to the recollection of such disasters.

The year began with the Tet Offensive of January 31st, when North Vietnamese forces launched a co-ordinated attack on the major cities of the South, and penetrated to the inner suburbs of Saigon itself. It was the beginning of the end for the Americans in south east Asia, though no one, especially not the US military-industrial complex, realised it at the time.

For us in Europe, Vietnam was something to be protested against, an affront to our supposed liberal ideals and sense of fair play; for Americans, it was an immediate and daily agony not only for the young men floundering in the paddy fields, but for the families and friends at home, watching the nightly television bulletins of horror and carnage, hearing the endlessly escalating body-counts.

One evening in that Irish bar in San Francisco, when I was taking a break from making a fool of myself behind an unmanageable guitar, I spoke to a young man home on leave from the war. I can still see his deadened eyes. Matter-offactly he described to me how, in retaliation for a Viet Cong atrocity, his platoon had captured a Viet Cong officer and attached him by arms and legs to four Jeeps which were then driven off in four directions.

Death was an almost palpable presence in the air that year. In April, Martin Luther King was assassinated; on June 3rd, Andy Warhol was shot and wounded, and it must have added to that publicity-hunter's pain when two days later he was spectacularly upstaged by the murder of Robert Kennedy. In London airport, groggy from jet-lag, I saw the newspaper headline, Kennedy Assassinated, and wondered why on earth someone should be reading a five-year-old newspaper.

In the second week of August came the black riots in the Watts district of Los Angeles. On August 21st, the Russians invaded Czechoslovakia. On the 29th, during the Democratic convention in Chicago, Mayor Daley's police force batoned and bludgeoned anti-war protesters in front of the television cameras. And in October, Derry "exploded in rioting", as the newspapers used to have it in those days.

And all the while, almost unnoticed, the Biafran war, one of the dirtiest and cruellest of the post-war period, was grinding on. Give peace a chance? That, as Joni Mitchell sang, was just a dream some of us had . . .

There were villains. When in France in May the student riots "erupted" - another favoured verb of the time - we sat around the television set in Parker Street watching in disbelief as what seemed to us the Second French Revolution brought mayhem to the streets of Paris. General de Gaulle had disappeared, crossed the border to seek asylum in Germany, some said; De Gaulle, symbol of French inflexibility and champion of la gloire, on the run from a ragtag army of university students!

Already, Lyndon Johnson had retired from the fray. I was a passenger in a crowded car - and American cars in those pre-oil shock days could accommodate quite a crowd - when LBJ came on the radio to announce that he would not stand for another term as president. We cheered. Looking back from now, when I regard Johnson as one of the great US presidents of the century, certainly in the domestic sphere, I acknowledge that tears would have been more apt to the occasion.

And we would have wept, had we known that apres Johnson would come le deluge of Nixon and, after the brief respite of the Carter presidency, the long years of greed politics under Ronald Reagan and his bunch of crooks. But how could we, the children of light, know what darkness lay ahead? As Basil Bunting has it, at the close of his great poem "Brigflatts", "Who, swinging his axe/ to fell kings/ gathers where we go?" Certainly, in the summer of '68, we did not dream that, from there, we would find ourselves here.

Series concluded