--- Mary Douglas, How Institutions Think (1986), p. 69
In context:
Every ten years or so classroom text books go out of date. Their need to be revised is in some part due to new work in science or to the deeper delving of historians. Much more, it is because science has come to seem over-religious or scandalously irreligious (Nelkin 1977), or because the history of the last decade gives a wrong political feeling (Fitzgerald 1979). In the intervening years, some slogans have become risible, some words have become empty, and others too full, holding too much cruelty or bitterness to modern ears. Some names count for more, and others that count for less are due to be struck out. The revisionary effort is not aimed at producing the perfect optic flat. The mirror, if that is what history is, distorts as much after revision as it did before. The aim of revision is to get the distortions to match the mood of the present times. But the mirror is a poor metaphor of the public memory. The seeker after historical truth is not trying to get a clearer image of his own face, or even a more flattering image. Conscious tinkering and remaking is only a small part of the shaping of the past. When we look closely at the construction of past time, we find the process has very little to do with the past at all and everything to do with the present. Institutions create shadowed places in which nothing can be seen and no questions asked. They make other areas show finely discriminated detail, which is closely scrutinized and ordered.
