So far our analysis has assumed that value scales and supply and demand schedules remain constant until equilibrium is reached. Yet the value scales of human beings change continually, so that a precise equilibrium may not always be attained. At any point in time, however, the free market is moving toward such equilibrium. Furthermore, the unhampered market is always moving toward the elimination of shortages and surpluses. A shortage or surplus may come into temporary existence, as a result of an unanticipated change in conditions; however, the bidding process in the resulting sellers' or buyers' market begins to rectify the imbalance immediately—or as rapidly as human beings are capable of recognizing and responding to such a situation.

In particular, any surplus of labor—i. e., unwanted unemployment—is quickly eliminated from the free market. As with any other good, a temporary surplus in any specific labor market may result from unanticipated changes in conditions. Such surpluses, known to economists as "frictional" unemployment, are generated essentially by workers who are "between" jobs. For example, after meeting Crusoe, Friday "lost his job" as a bamboo-pole maker (pp. 4.5:22-6). He quickly found a more profitable position as a berry-picker, however. (The peculiar language used here is typical of contemporary economic journalism and reflects a misplaced concern with "jobs" rather than with productivity; cf. p. 4.4:23.) Friday's "frictional" unemployment was an ephemeral condition, necessary to achieve a more efficient allocation of means to ends, which both men found beneficial.