The 20th century was hardly short of landmark historical events. You don't need to know about most of them in any profound sense – you can enjoy the convenience of the internet or a life free of measles without deep knowledge of the history of computing or vaccination.
But there are a few moments in history that everyone needs to know about because what they tell us is directly relevant to our lives today.
The first landing on the moon half a century ago is one. That was an inspirational event that showed that humans can achieve the almost impossible if we put our minds to it and work together. It's a particularly useful touchstone as we face the daunting challenge of climate change. Yet there is a whole generation that is almost unaware it even occurred.
The Holocaust is another. Every year global Holocaust awareness is surveyed and every year it gets a little lower.
There is an important difference between people who are ignorant of the Holocaust and people who deny it. People who are ignorant allow Holocausts to happen because they haven't had a chance to learn its lesson; people who deny it occurred are the sort of people who make it happen.
But five per cent of people in Britain say the Holocaust didn't happen and a third of Americans say the actual number of Jews killed was two million not six.
It's particularly paradoxical given both countries played a significant part in the war whose conclusion brought the Holocaust to an end. You'd think their citizens might like to know a bit about what their grandparents risked and in many cases lost their lives for.
There is no reason to think the figures would be much different here, where the events are so much further removed and the Jewish population so much less visible. New Zealand-based, online Holocaust denial is out there and not hard to find if you go looking for it.
It's no surprise in light of these figures that a quarter of Europeans also believe Jews have too much influence in business and finance. Everyone knows where that stereotype leads – or they would if they knew how the Holocaust occurred.
The Holocaust is such an extreme, horrifying event that some might argue it's not necessary to inflict the burden of knowing about it onto young people. But it was hardly a one-off anomaly in human history, which shows attempts to obliterate nations from the face of the Earth going back to biblical times, when Samuel ordered the destruction of the people of Amalek. And Rwanda in 1994 shows the instinct is still alive.
But the word itself only came into being relatively recently, coined in 1944 by Polish Jewish lawyer Raphael Lemkin who had been a student of the phenomenon since becoming aware of the Turkish massacres of Armenians after World War I.
It was certainly unprecedented in its scale and devastation, but as Holocaust researcher Harry D Wall sums up: "Holocaust education also serves a broader purpose, since it can provide a historical context to understand and prevent other atrocities. The Holocaust began with words, racial stereotyping and demonisation – and that has also been the prelude to mass violence around the globe."
Nazism taught us how fragile civilised values are – how easily normal, decent people can be turned into functioning psychopaths performing acts their better selves would never have countenanced. It not only begins but flourishes in ignorance.
And another thing: Prince Harry has become grumpy and aloof since his marriage according to royal biographer Duncan Larcombe. Prince Phillip must be breathing a sigh of relief that the kid's finally got with the programme.