Every one of those Economic details can be considered intelligently, readily and accurately, through the medium of the three Basic Facts, into one or another of which must fall, not only that barrel of potatoes and all the details of its production, but also the entire stock of the store, and of all other stores, and every Economic agency back of them to the very beginning of each productive process through which they have passed. All Economic details, the familiar and the unfamiliar, the obvious and the mysterious, the known and the unknown, generalize with precision into the three Basic Facts of Economics--Artificial Objects, Natural Resources and Man. Natural Resources are the source and the indispensable condition at every stage, from beginning to end, in the production of every kind of satisfaction for human wants. Man is the active agent at all stages. Artificial Objects constitute the category into which each result generalizes at each stage of production. From Economic particulars we derive knowledge of Economic detail and skill in applying that knowledge; but only from their correct generalization can we derive Economic wisdom. Thinking _about_ the three Basic Facts is necessary to an understanding of their mutual relations; thinking _from_ them is necessary to an understanding of the mutual relations of their constituent parts. Reversely, we must think from Man to Man-power of numerous kinds, both mental and physical; from Natural Resources to soil, minerals, air, water, building sites, and so on; from Artificial Objects to houses, tools, machinery, food, clothing, et cetera. In another form of statement, the Economic student must know and understand the comprehensive categories or Basic Facts in order to grasp the Why of Economic adjustments, the natural relationship of Economic effects and causes. To understand the How, he must also know and understand the little facts of Economic specialization, such as the mutual relations of the details which go to make up those wholes--the particular facts, for instance, of agriculture or architecture or engineering or merchandizing or manufacturing or banking or professional service,--as well as their three comprehensive classifications or Basic Facts--Man, Natural Resources and Artificial Objects.