How high can inflation go?

I was a Special Adviser with the Labour Government in the mid 1970s when inflation briefly reached around 25%. We were told by the media that a society could not survive an inflation level of this order.
I remembered this as I read a report on the current rate of inflation in Zimbabwe. Currently the official figure is now a staggering 8,000% – but unofficially it is even higher and it is going to rise even further.
I was technically inside Zimbabwe a few years ago during a holiday in South Africa when I visited Victoria Falls [my account here] and I feel desperately sorry for its suffering people.