Now, in skill, as thus defined, we have doubtless a correct explanation of how mere labour--the manual effort of the individual--may produce, in the case of some men, goods whose value is great, and goods, in the case of other men, whose value is comparatively small; and since some epochs are more fertile in developed skill than others, an equal amount of labour on the part of the same community may produce, in one century, goods of greater aggregate value than it was able to produce in the century that went before it. But these goods, whose superior value is due to exceptional skill--or, as would commonly be said, to qualities of superior craftsmanship--though they form some of the most coveted articles of the wealth of the modern world, are not typical of it; and from the point of view of the majority, they are the part of it which is least important. The goods whose value is due to exceptional craftsmanship--such as an illuminated manuscript, for example, or a vase by Benvenuto Cellini--are always few in number, and can be possessed by the few only. The distinctive feature of wealth-production in the modern world, on the contrary, is the multiplication of goods relatively to the number of the producers of them, and the consequent cheapening of each article individually. The skill of the craftsman gives an exceptional value to the particular articles on which his own hands are engaged. It does not communicate itself to the labour of the ordinary men around him. The agency which causes the increasing and sustains the increased output of necessaries, comforts, and conveniences in the progressive nations of to-day must necessarily be an agency of some kind or other which raises the productivity of industrial exertion as a whole. Those, therefore, who, in spite of the fact that the productivity of modern communities has, relatively to their numbers, undergone an increase which is general, still maintain that the sole productive agency is labour, must seek for an explanation of this increase in some other fact than skill.