摘要
There is an attractive analogy between nature and industry, based on the similarity of natural functions and certain industrial activities. For instance, animals ingest (eat) and digest food. Finally, there are metabolic wastes. Firms are analogous to organisms in several respects, insofar as they consume material resources, process (digest) them and produce output products and excrete wastes. Firms, like organisms, also compete with each other for resources. Curiously enough, one of the apparent differences between natural and man-made systems is actually not one; like the industrial system, the natural system does not recycle everything.