There is a moment in Ernest Hemingway’s “For Whom the Bell Tolls,” just on the precipice of the culminating battle — the protagonist, Robert Jordan, is to use a group of locals during the Spanish Civil War to blow up a bridge. Robert Jordan has fallen in love with one of the local women during his Green Beret-style warfare, and from time to time he allows himself the fantasy of believing that they will one day have a future together. Those dreams are curtailed by the harsh reality of the mission he is on. The mission is falling apart minute by minute, in contrast to the glorious minutes he spends with her.
As he lays next to her, on the morning of the final battle, the dutiful soldier Robert Jordan allows his mind to wander. His heart begins to ache for all the things he could have had, but never will.
How little we know of what there is to know. I wish that I were going to live a long time instead of going to die today because I have learned much about life in these four days; more, I think, than in all the other time. I’d like to be an old man and to really know. I wonder if you keep on learning or if there is only a certain amount each man can understand. I thought I knew about so many things that I know nothing of. I wish there was more time.”
There is a special clarity here that can only be gained from being in a position where everything is about to be stripped away. You can read about combat, you can study it and explore the facets of it — you can probably get to a point where you understand the psychology, technicalities and statistics better than those who have experienced it. But it is still separate from the experience itself, (though the experience is not limited to soldiers).