"And purpose is what keeps him from running. Without purpose men will run. They will act out their dreams, and they will run and run, like animals in stampede. It is purpose that keeps men at their posts to fight. Only purpose." (Going After Cacciato, p. 178). If there is no reason for the soldier to be fighting, he will abandon his post. Purpose is what compels a soldier to do his job, because it gives him a reason to fight.