As the second of the [general] causes of superior productiveness, we may rank the greater energy of labor. By this is not to be understood occasional, but regular and habitual energy. The third element which determines the productiveness of the labor of a community is the skill and knowledge therein existing, whether it be the skill and knowledge of the laborers themselves or of those who direct their labor. That the productiveness of the labor of a people is limited by their knowledge of the arts of life is self-evident, and that any progress in those arts, any improved application of the objects or powers of nature to industrial uses, enables the same quantity and intensity of labor to raise a greater produce. One principal department of these improvements consists in the invention and use of tools and machinery.(114) The deficiency of practical good sense, which renders the majority of the laboring-class such bad calculators—which makes, for instance, their domestic economy so improvident, lax, and irregular—must disqualify them for any but a low grade of intelligent labor, and render their industry far less productive than with equal energy it otherwise might be. The moral qualities of the laborers are fully as important to the efficiency and worth of their labor as the intellectual. Independently of the effects of intemperance upon their bodily and mental faculties, and of flighty, unsteady habits upon the energy and continuity of their work (points so easily understood as not to require being insisted upon), it is well worthy of meditation how much of the aggregate effect of their labor depends on their trustworthiness. Among the secondary causes which determine the productiveness of productive agents, the most important is Security. By security I mean the completeness of the protection which society affords to its members. § 2. Combination and Division of Labor Increase Productiveness.