Collective memory is imperfect. Together we only remember a fraction of what happened. But why?
Collective memories remember the most about the beginning, the middle, and the end. For example, Americans remember the most from the second World War as three major events: the bombing of Pearl Harbor (the beginning), the D-Day landings (the turning-point), and the dropping of the atomic bombs on Hiroshima and Nagasaki (the end). Most other events were forgotten.
The second reason is “mnemonic silence.” One study found that the words of high-profile persons about the past can shape the public memory.
For example, most of us don’t remember the Spanish flu. This killed more people than World War I. The doctors’ reason for not speaking about it is that they couldn’t help cure it. The same is true for politicians, who were also helpless.