Events like the Holocaust must never be allowed to recur: this was Mr Cowen's message on a visit to Yad Vashem, the Jerusalem site where the victims are remembered.
Some nations are luckier than others. The Irish emerged from the last century more or less unscathed. The Jews were a lot less fortunate: six million dead; whole communities wiped out or scattered; trauma and suffering beyond belief or measure.
The Minister for Foreign Affairs took time out yesterday from his diplomatic tour of the Middle East to pay homage to the victims of the Holocaust at Yad Vashem, the impressive museum located on a hill above Jerusalem.
His learned guide, Dr Robert Rozett, explained that Yad Vashem was Hebrew for "eternal memorial". The phrase is taken from the Book of Isaiah, and a visit to Yad Vashem is a standard ingredient of any Israeli visit by a foreign dignitary. The then US president, Mr Bill Clinton, for example, was reportedly moved to tears by the experience, as no doubt were many others.
The site is a model of its kind, combining appeals to the emotions with historical documentation and analysis and a quiet, tragic dignity. Like previous distinguished visitors, the minister rekindled the eternal flame which burns in memory of the six million.
Wearing a skullcap as a sign of respect, he laid a wreath on a stone slab which covers the ashes of different victims of the Holocaust.
Dr Rozett took his Irish visitors over the historical ground, explaining the background to the rise of Nazism. To illustrate German hyperinflation in the 1920s there was a photograph of a woman stoking her fire with banknotes. The huge popular enthusiasm for Hitler despite or perhaps even because of his anti-semitic policies was well-documented.
Then the tragic aftermath: Kristallnacht (the night of broken glass) when Jews were attacked all over Germany, the first concentration camps, the Warsaw Ghetto, the ravages of the SS, and ultimately the "final solution".
Canisters of Zyklon B, the fatal chemical used in the gas chambers, are one of the museum's more disturbing exhibits.
Despite being under pressure of time, the minister showed a keen interest in the various displays. There were many moving photographs of children and elderly people who perished in the great storm of hatred.
Equally striking were the images of humiliation: Viennese Jews compelled to clean the streets of their city with scrubbing brushes, a woman paraded with an insulting placard for consorting with a Jewish man, a group of victims posing for a photograph prior to their execution.
The astonishing horrors of that period put even today's disturbing and violent events in perspective. In the visitors' book, Mr Cowen wrote: "Yad Vashem reminds us of the need to remember; not just to honour the victims of the Holocaust but to strengthen our determination that its like will never be permitted to recur."
On his way out, the minister encountered the former Israeli Ambassador to Ireland, Mr Zvi Gabay, who now deals with Asian affairs and was taking a Chinese delegation around the site.
Meanwhile, the news on the radio remained bleak.
The Irish diplomatic effort is based on bringing an end to violence so the two sides can come together. It is a modest contribution but it may help because, as the Holocaust proved, for evil to triumph it is only necessary for good people to do nothing.