is the aim of social institutions to harmonize individual and social interests in the pursuit of wealth, to force men into lines of action where individual acquisition adds to the sum of social utilities. But there are many marginal cases where human justice discriminates only in a bungling way, and many controverted questions arise at the meeting-point of ethics, economics, and law. [Sidenote: Industries are socially more or less productive] 5. _In this sense, productive industries may be distinguished from unproductive ones._ The old distinction between productive and unproductive labor rested on the idea that production must be embodied in material and lasting form. We have rejected this for the thought that the tests of production are to be found in feeling, not in outward things. The distinction, therefore, between productive and unproductive labor must now be of a very different kind. Viewed from the social standpoint, the efforts of men may be seen to be directed along more or less productive lines. Enterprise and effort shade off from the more to the less productive, from the extreme where the value is a net addition to wealth, through other cases where one's gain is partly at the cost of others, to fraud and crime where there is merely a transfer of ownership. § II. COMBINATION OF THE FACTORS [Sidenote: The factors of production defined] 1. _The various parts, materials, and agents that unite to form products are called the factors of production._ In a general sense every separate thing that enters into industry is a factor; as, in agriculture, for example, the seed, plows, fields, fences, barns, cattle, labor. But usually in economic discussion, these numerous factors are grouped in large classes. The main factors are two, variously named as man and nature, or labor and material agents, or humanity and wealth. Rejecting, as we have, the old view as to the nature of consumption goods and as to the nature and possibility of the distinction between "land" and artificial capital, we class under wealth all material economic agents whatsoever. The discussion of labor and wages has broadly laid down the principles that apply to the value of human effort, but the factor of directing energy presents in modern society so many important features that it calls for special and fuller consideration. [Sidenote: Progressive stages of control over natural conditions]