Experience has proved time and again that any machine has a particular capacity at which it can be most efficiently operated. A simple stone crusher kept half full is running at a loss; if crowded and speeded up it will wear and break unduly. It would be foolish to run continually a 50 horse-power engine to serve a 2 horse-power motor. An electric light plant is most economical when operated at its “capacity.” Horse and wagons, motor trucks, railways, canals, and ships, are but machines, and the law holds with all of them that they are most efficient when operated at their proper capacity. Another economic truth is that the unit cost of production is usually lowest when the output is great. Quantity production is the goal of practically all successful manufacturing enterprises. Automatic and near-automatic machines replace the human hand. One person by the aid of mechanical and electrical devices produces as much in the same time as could a score or even a hundred without such help formerly. The chief reason why quantity production is cheaper than individual production is that it allows for a division of labor, a separation of the preparing processes into several operations or occupations. Growing the grain, transporting it to market, grinding it into flour, baking it into bread, and selling the bread, indicate some of the several occupations, that arise in the simple preparation of “our daily bread.” The meat-packing industry affords an excellent example of the principle: The animal is surveyed and “laid off like a map”; and each workman as the carcass passes him has one operation to perform. One man sticks the pig, another scalds it, another pulls the hair from a particular portion of the body, one cuts the slits for the gambols, another inserts the sticks, still others hoist the body to the hanger, and so on as it proceeds along its course scores of persons are each doing a very limited portion of the work until the entire animal is prepared and packed for shipment. The workmen are classified and the highest paid are put to the most delicate or important parts while for the less delicate and less important duties the pay is very much lower. But each workman having only a small variety of work to perform soon becomes adept and can do a much greater amount than if he attempted the entire round of labor. The building of automobiles wherein materials start from different places and eventually coalesce as they proceed on their journey through the shops by each workman as they pass adding one thing or performing one operation until the whole emerges a complete machine ready to run away under its own power, is another case in point.