Does this not explain life sometimes?, from The Red Badge of Courage:
He suddenly lost concern for himself, and forgot to look at a menacing fate. He became not a man but a member. He felt that something of which he was a part--a regiment, an army, a cause, or a country--was in a crisis. He was welded into a common personality which was dominated by a single desire. For some moments he could not flee no more than a little finger can commit a revolution form a hand.