But apart from this general trend the line of development is not single.

As concerns economic theory, the development in other respects runs on two divergent lines.

So far as regards the selective conservation of capacities or aptitudes in individuals, these two lines may be called the pecuniary and the industrial.

As regards the conservation of propensities, spiritual attitude, or animus, the two may be called the invidious or self-regarding and the non-invidious or economical.

As regards the intellectual or cognitive bent of the two directions of growth, the former may be characterized as the personal standpoint, of conation, qualitative relation, status, or worth; the latter as the impersonal standpoint, of sequence, quantitative relation, mechanical efficiency, or use.
The pecuniary employments call into action chiefly the former of these two ranges of aptitudes and propensities, and act selectively to conserve them in the population.