The commercial storm leaves its path strewn with ruin. When it is over there is calm, but a dull, heavy calm.

Knowledge is our most powerful engine of production.

Consumption may be regarded as negative production.

In the absence of any short term in common use to represent all desirable things, or things that satisfy human wants, we may use the term Goods for that purpose.

Again, most of the chief distinctions marked by economic terms are differences not of kind but of degree.

Material goods consist of useful material things, and of all rights to hold, or use, or derive benefits from material things, or to receive them at a future time.

Though a simple book can be written on selected topics, the central doctrines of economics are not simple and cannot be made so.