The consideration originates in the thesis that the memory consists in continuous reconstruction of the past. By means of intended or unintended memorizing, remembering and forgetting, thus keeping former experience of an individual in mind and its treating, the continuity of his life is found.
This process does not run separately, but it is conditioned upon the experience of a group an individual identifies himself with, a group that creates the social framework for each process of memorizing. The individual memory thus develops, communicating with the social environment in which an individual moves and participating in constructing the collective memory.
The above is obvious e.g. when analyzing the Holocaust memoirs.