From 1847 until 1938, John Bates Clark, a well-known American economist, was alive. His contributions to the theory of marginal productivity and the notion that employees add to the value of their pay have made him famous. In one of his articles, he explained an economic process that is similar to a huge assembly line, with each worker contributing a tiny portion before the final product is passed on.

Envision a complex river system in which water flows through innumerable branches, each of which contributes a single droplet, culminating in a powerful downstream current. Similarly, according to Clark, employees engage in a complex web of production processes, contributing their own special abilities or efforts to materials that are transferred from one individual to another. Every employee contributes something necessary, but the finished product is frequently finished much later.

According to Clark, products are made in this disjointed fashion and then vanish into the marketplace when they are prepared for sale. These commercial routes can be as hard to track as the origin of a river, particularly when goods are shipped all over the world before they are purchased. Similar to how water sources are connected through underground streams and rivers, the concept emphasizes how economic activities are interdependent and interconnected.

The complexity of industrial production and the way that individual contributions fit into the overall framework of economic activity are both demonstrated by Clark's observation. Each worker's labor is only a single component in the larger scheme of manufacturing and trade, much like a single drop of rain becomes a part of an enormous river system.