Which two sentences in this excerpt from John Steinbeck's "Symptoms" address the theme of soldiers being reluctant to talk about their experiences in war?

If they had been reticent men it would have been different, but some of them were talkers and some were even boasters. They would discuss their experiences right up to the time of battle and then suddenly they wouldn't talk anymore. This was considered heroic in them. It was thought that they had seen or done was so horrible that they didn't want to bring it back to haunt them or their listeners. But many of these men had no such consideration in any other field.
Only recently have I found what seems to be a reasonable explanation, and the answer is simple. They did not and do not remember--and the worse the battle was, the less they remember.