External economies are those gains, benefits or other advantages of a human action which necessarily go to a person or firm that does not participate in the action. Such advantageous results are often neglected in the economic calculations which determine whether or not an action is or will be considered profitable. An example of such an incidental benefit would be the gain A's neighbors reap from a fence built by A on their boundary lines.
- Percy L. Greaves, Jr. "Mises Made Easier ", 1974. Referenced 2014-07-11.