When I have difficulty understanding the present, I turn to the past, and often to the Second World War. What stands out is the extraordinarily narrow margin of survival in the terrible spring of 1940. The free world left it very late in recognising the deadly danger building through the 1930s.
Looking back, we might wonder how so many people failed to see what was developing - and failed to act.
Today we again face something terrible. This time it is not external, but the consequences of our own actions, and the battle to be fought is the struggle to discipline ourselves.
And the first part of the struggle is - like the alcoholic on a downhill path - facing up to who we are and what we are doing.
In the 1930s there were people who said we could not afford the cost of the weapons needed to deter Hitler, and there were others who said that he was really a very nice man. And today there are people who say that climate change isn't happening because they have found a website which says so, and that in any case we can't afford to do anything about it.
The irony is that solutions are simple. We have a threefold crisis. We are pouring out too much greenhouse gas and destabilising the climate. We are also burning up oil and gas faster than we discover new fields. And we need growth industries to invest in to revive the global economy.
President Obama has now shown the way. Invest in green technology and we boost the economy - while cutting back on greenhouse gas production and slowing the rate of depletion of our finite stocks of oil and gas.
How on earth has it taken us so long to realise something so obvious? But more important - how long will it now take us to put it into effect?
Decades of delay in acting on climate change raise the question: how on earth are our …