competition should, so long as that contract was in force, be debarred from showing any preference in his or its purchases and sales, by giving more or less favorable prices to any person or firm than those quoted to any other person or firm. To enforce this requirement and prevent its evasion it is necessary to provide also that prices shall be public and that they shall not be altered without due notice. The requirement of publicity might be best effected by providing that the contract restricting competition should contain a schedule of prices, which would usually be the case in any event.
While this may seem like quite an assumption of authority on the part of the State, it is exactly what trusts and trade associations are striving to effect, though with the important qualification that when occasion, in the shape of an obnoxious competitor, requires, they wish to be at liberty to put prices up or down at short notice and exercise their preferences as they choose.
Let us now see what we would effect by the enforcement of this principle of non-discrimination. We have explained in the chapter on combinations in trade how one monopoly gains strength by alliance with another; as when the firms belonging to the car-spring combination