War of the Classes by Jack London

In a competitive society, where men struggle with one another for food and shelter, what is more natural than that generosity, when it diminishes the food and shelter of men other than he who is generous, should be held an accursed thing? Wise old saws to the contrary, he who takes from a man's purse takes from his existence. To strike at a man's food and shelter is to strike at his life; and in a society organized on a tooth-and-nail basis, such an act, performed though it may be under the guise of generosity, is none the less menacing and terrible.

It is for this reason that a laborer is so fiercely hostile to another laborer who offers to work for less pay or longer hours. To hold his place, (which is to live), he must offset this offer by another equally liberal, which is equivalent to giving away somewhat from the food and shelter he enjoys. To sell his day's work for $2, instead of $2.50, means that he, his wife, and his children will not have so good a roof over their heads, so warm clothes on their backs, so substantial food in their stomachs. Meat will be bought less frequently and it will be tougher and less nutritious, stout new shoes will go less often on the children's feet, and disease and death will be more imminent in a cheaper house and neighborhood.