Unemployment arises because the budget deficit is too small relative to the desires of the private sector to meet its tax obligations and to save and to hold money for transactions purposes. Mass unemployment is a macroeconomic phenomenon and can never be a "real wage" problem. William Vickrey argued that "the 'deficit' is not an economic sin but an economic necessity. Its most important function is to be the means whereby purchasing power not spent on consumption, nor recycled into income by the private creation of net capital, is recycled into purchasing power by government borrowing and spending. Purchasing power not so recycled becomes non-purchase, non-sales, non-production, and unemployment."