In addition to land, labor, and capital factors, Crusoe must have an underlying idea or recipe, conceptually similar to our structure-of-production diagram, but also specifying the required quantities of the various factors (which we omitted for simplicity). Here we assume that Crusoe has already finished planning this process and consequently does not devote further resources to developing its underlying idea. Unlike land, labor, and capital, an idea is not "used up" in the production process. An idea or recipe need only be produced once and can then be reapplied as often as it is needed. Consequently, it ceases to be an end that a human being must act to gain and/or keep—and is therefore no longer technically a praxeological good. If this distinction seems unclear, it may help to review the definitions of good (as a noun) and subjective value in the Glossary.

Of course, new ideas are often of enormous value to human beings. Nevertheless, once a particular idea has been developed, people no longer strive to increase their "stock" of it.