Some time ago I read a book that served as a history of PTSD  and one of the most remarkable aspects of the history of PTSD is that the disease was discovered so recently, in the aftermath of the Vietnam War. To be sure, the general constellation of symptoms that became defined as PTSD were known before then. They were considered shell shock in World War I and World War II and combat fatigue in the Civil War. Let us note that PTSD was associated with warfare, and it was soldiers in warfare that had the shell shock and the combat fatigue, and it was thought, apparently, that this particular problem was only something that resulted from warfare and that it was short-term, such that when the fighting was over, there was no interest in the long term ramifications of the warfare that had been fought. Once the war was won, the soldiers were home and they had to muddle through life on their own or with the help of their relatives or the support of their neighbors and local communities, and the larger culture was not so interested in their suffering.
Yet something changed after the Vietnam War. For one, that war was the first war that the United States had ever unequivocally lost. For another, a large part of the fallout concerned the trouble faced by returning veterans who were in obvious suffering for a long time after the war was over. When the shooting stopped, people did not get better. Of course, these had always been a problem, going back a long time, but it had never happened to reach public attention to any great degree. After World War I, for example, there were a variety of broken men who were unable to fully enjoy the fruits of the lifestyle of the roaring 1920’s. I happen to be descended from two of them , veterans of that terrible war who had been gassed and who ultimately died of the consequences of their war wounds. Yet our nation does not even have a memorial for these men. Even at the time, when veterans sought somewhat early benefits during the early part of the Great Depression, they were thought to be lazy and selfish good-for-nothings. This was also true after the Civil War when the suffering veterans seeking to gain benefits were thought of as wastrels and scoundrels rather than people whose suffering merited some sort of sacrifice on the part of the larger society on their behalf.
What changes about the past when we understand ourselves? Well, when we look at the past, we see PTSD where people at the time saw discrete and short-term problems, and we see these different syndromes, and other descriptions of the survivors of war or of other horrors like rape  and we see them as part of a long and connected context, a context that was missing to those who lived in the past. We have a box to put these experiences in and a label to put on them that others did not in the past, and so they tended to view the suffering in isolation, and not as part of larger picture. There are some consequences of this, not least in the fact that while ancient historiography glorified the degradation of enemies in warfare, contemporary writers of historical fiction tend to focus on the PTSD of the victim of an Assyrian gang rape rather than the claims of Assyrian kings to have piled tens of thousands of skulls outside the smoldering ruins of some city whose king rebelled against their cruel domination. This is not to say that this changed focus is wrong, only that we care about things that the ancients did not care about, and what consumed their public architecture and their sources is either abhorrent or passe to our contemporary tastes, just like our contemporary fashions and fads will likely be tiresome or tedious or hideous to those who follow after us and who wonder how we could ever be so cruel and callous towards the fruit of the womb just as we cannot fathom the infanticide of ancient Rome or the child sacrifice of the Ancient Near East.
How are we to resolve the fact that we see the past so much more clearly sometimes than we see ourselves and our own times and our own situations? There is often a great benefit in having a sense of distance from events that we are seeking to understand and analyze, because the more time and the more psychological distance we have, the more clearly we can see patterns and judge actions as wise or unwise, or tell the difference between lasting trends and passing fads. When we are seeing events come in real time, we cannot tell the difference between fads and trends, and our guesses are not likely to be very good. Yet we demand a snap analysis of events as they are happening  because we are not patient and we are not willing to wait to see how things turn out before we try to guess how they will turn out. Even speculation frees us from the burden of not knowing or having any idea, and so we will listen to anyone who can quickly form thoughts together rather than wait to see how things will really turn out. As is the case with something like PTSD, sometimes we do not want to see how things turn out, to see that what we thought would end once the shooting stopped or once the abuse was no longer happening instead carried on for a lifetime, and had consequences that last for generations. Often we shut our eyes to history not because it is irrelevant to us, but because we do not want to see the truth because it is too painful to reflect upon, and we do not trust ourselves to view it coldly and clearly.
 See, for example:
 See, for example: