Let it be emphasized once more, and especially to anyone inclined to a personally rewarding skepticism in these matters: for practical purposes, the financial memory should be assumed to last, at a maximum, no more than 20 years. This is normally the time it takes for the recollection of one disaster to be erased and for some variant on previous dementia to come forward to capture the financial mind. It is also the time generally required for a new generation to enter the scene, impressed, as had been its predecessors, with its own innovative genius.
John Kenneth Galbraith, A Short History of Financial Euphoria
memory, political-memory