Thinking more about this…
An undamaged (so to speak) brain perceives direct experience as continuous, but direct experience is not the same as history. Silas Weir Mitchell (in the linked post) wrote about injured Civil War veterans; Marc Bloch uses the following example in The Historian’s Craft:
Let us suppose that a military commander has just won a victory. That, immediately, he sets to work writing an account with his own hand. That it was he who conceived the plan of the battle, and that it was he who directed it. And finally that, thanks to the moderate size of the field (for in order to sharpen the argument, we are imagining a battle of former times, drawn up in a confined space), he has been able to see almost the entire conflict develop before his eyes. Nevertheless, we cannot doubt that, in more than one essential episode, he will be forced to refer to the reports of his lieutenants. In acting thus as narrator, he would only be behaving as he had a few hours before in the action. Then as commander, regulating the movements of his troops to the swaying tide of battle, what sort of information shall we think to have served him best? Was it the rather confused scenes viewed through his binoculars, or the reports brought in hot haste by the couriers and aides-de-camp? Seldom can a leader of troops be his own observer. Meanwhile, even in so favorable a hypothesis as this, what has become of that marvel of “direct” observation which is claimed as the prerogative of the studies of the present?
No doubt the commander’s experience of the battle was continuous; no doubt his account of the battle will fail to replicate that continuity. But it is not accurate to say that the former is the product of a healthy brain while the latter, no matter how thoroughly constructed, is doomed to resemble the product of a damaged one. The commander, in producing his account, is trying to capture more than what he experienced – more than what any single participant in the battle experienced, and indeed, more than any single person could have experienced. If history always fails to reproduce the past as it appeared to the people who lived in it, it is not just because historians’ access to the past is necessarily limited, it is also because historians are asked to do things no historical actor ever does when the past is still the present, and no living person does when the past is recalled as memory – history, at least in the form we know it today, is fundamentally unnatural.
Later Bloch writes:
Because the individual, narrowly restricted by his senses and power of concentration, never perceives more than a tiny patch of the vast tapestry of events, deeds, and words which form the destinies of a group, and because, moreover, he possesses an immediate awareness of only his own mental state, all knowledge of mankind, to whatever time it applies, will always derive a large part of its evidence from others. In this respect, the student of the present is scarcely any better off than the historian of the past.
If what historians do is more like producing than reproducing, why pay so much attention to the so-called irreproducibility of the past?
It is easy to see why this remoteness of the scholar from the object of his knowledge makes so strong an impression upon many historical theorists. It is because they think of history primarily in terms of events, even of episodes – of a history which, rightly or wrongly (and it is immaterial at the moment) attaches an extreme importance to the exact reconstruction of the actions, words, or attitudes of a few personages, brought together for a relatively brief scene, in which as in a classic tragedy, are marshaled all the forces of the critical moment: the day of a revolution, a battle, or a diplomatic interview.
Bloch concludes the paragraph with an example that shows why the brain-damage analogy can sound so plausible:
It is related that on September 2, 1792, the head of the Princess de Lamballe was paraded on the end of a pike under the windows of the royal family. Is this true or false? M. Pierre Caron, who has written an admirably honest book on the September Massacres, does not venture an opinion. Had he been permitted to watch the ghastly cortege in person from a tower in the Temple, he would have known what to think – at least if, preserving his scholarly detachment in these circumstances (as might be expected), and properly mistrustful of his own memory, he had further taken the precaution of making a note of his obvervations on the spot. Unquestionably, in such cases, the historian is mortified by comparing his position with that of a reliable witness of a present event. He is as if at the rear of a column, in which the news travels from the head back through the ranks. It is not a good vantage-point from which to gather correct information. Not so very long ago, during a relief march at night, I saw the word passed down the length of a column in this manner. “Look out! Shell holes to the left!” The last man received it in the form, “To the left!” took a step in that direction, and fell in.