Work, [Adam] Smith points out, is a reciprocal process: Workers form goods, and are, in turn, formed by their labors. Smith worries about the fate of people whose work, say, consists of drawing out wire, or straightening it, or cutting it, hour after hour, as in the famous first example of the division of labor, the pin factory, discussed in the opening pages of Book I. His anxieties center on “the understanding,” a broad and flexible concept in Enlightenment thought that could include a number of mental faculties, including memory, imagination, and reason. All of those faculties are on Smith’s mind here, but he is especially apprehensive about workers’ declining capacity for rational thought:“The understandings of the greater part of men are necessarily formed by their ordinary employments. The man whose whole life is spent in performing a few simple operations, of which the effects, too, are perhaps always the same, or very nearly the same, has no occasion to exert his understanding, or to exercise his invention, in finding out expedients for removing difficulties which never occur.”