Os Guinness points out that the principle of calling contradicts the market mentality.
Ironically, a "free market" does not create a society as fre as many think, for the constant pricing and charging of everything acts like a series of customs tolls blocking the free flow of ideas and relationships. Equally ironically, we eventually cannot afford what we most desire - deep relationships. For if "time is money" and people take time, then the "opportunity costs" of relationships (the gain that we would earn by doing something else) will be prohibitive and intimate friendships will be few. "Spending" time with friends is costly; we could "invest" it better elsewhere.
The spirit of calling counters this spirit of commerce by knocking holes in the ice. Thus there are, if you like, two economies - a "calling economy" as well as a "commercial economy" - and for followers of Christ the former, not the latter, is supreme. Contrary to the ways of commerce, calling means that life is lived for God's sake or for its own sake under God. Intrinsic satisfaction outweighs external rewards, such as pay, advancement, and recognition.