“One of the rules that emerges from a consideration of the factors that promote self-sacrifice is that we are less ready to die for what we have or are than for what we wish to have and to be. It is a perplexing and unpleasant truth that when men already have “something worth fighting for,” they do not feel like fighting. People who live full, worthwhile lives are not usually ready to die for their own interests nor for their country nor for a holy cause.”