1. _Man and his welfare are the end and aim of the economic process._ The starting point of industry is wants; the goal is welfare. Momentary gratification is only a way-station, not the journey's end. Too often, in economic reasoning, things are looked at from the employer's point of view. The older writers, such as Ricardo and Mill, were inclined to take what John B. Clark has called the "feed and work" view,--the view that the workman is merely an agent of production, a means to an end; that his food, the same as coal for an engine, is to be thought of rather as employer's cost than as consumer's gratification. But, in the broader view, the welfare of men as men is the subject most worthy of economic study. The workman's food is to gratify his hunger, primarily; not merely to make him a better working machine. This reverses the order of the older reasoning. The use made of the income is itself a kind of production--its last stage. Is the process, on the whole, worth while? This can only be judged by finding whether, on the whole, the welfare of man has been furthered. [Sidenote: The marginal application of income] 2. _An income yields the maximum gratification when it is apportioned among goods so that their marginal utilities, as nearly as possible, are equal._ Even a small income is income capable of many applications. The choice lies among many thousands of articles. Utility varies not only according to the kinds of good, but according to the varying quantities of each. Every moment, therefore, the conditions of a choice are changing. The best use of income forbids the purchase of an additional unit of any good unless it affords the highest gratification obtainable, at the moment, at an equal price. Various circumstances prevent the exact application of this rule. Expenditure is a matter of habit, in large measure, rather than a matter of judgment. The knowledge needed for a rational choice very often is lacking. Appetites change, making unwise the old purchases, yet men go on buying the same things in the same proportions simply because a readjustment that would give greater gratification requires thought. Finally, the best economic adjustment must conform to the abiding physical and moral welfare of the user, not to a temporary impulse; and such a choice is far more difficult than that of the temporary good. [Sidenote: Progress and the refinement of desires]