This is a serious analysis of a ridiculous subject, which is of course the opposite of what is usual in economics. - Paul Krugman

First, most of the speculation about the superiority of the communist system - including the popular view that Western economies could painlessly accelerate their own growth by borrowing some aspects of that system - was off base. Rapid growth was based entirely on one attribute: the willingness to save, to sacrifice current consumption for the sake of future production. The communist example offered no hint of a free lunch.
Second, the economic analysis of communist countries' growth implied some future limits to their industrial expansion - in other words, implied that a naive projection of their past growth rates into the future was likely to greatly overstate their real prospects. Economic growth that is based on expansion of inputs, rather than on growth in output per unit of input, is inevitably subject to diminishing returns. It was simply not possible for the Soviet economies to sustain the rates of growth of labor force participation, average education levels, and above all the physical capital stock that had prevailed in previous years. Communist growth would predictably slow down, perhaps drastically.

When the economy is in a depression, scarcity ceases to rule. Productive resources sit idle, so that it is possible to have more of some things without having less of others; free lunches are all around. As a result, all the usual rules of economics are stood on their head; we enter a looking-glass world in which virtue is vice and prudence is folly. Thrift hurts our future prospects; sound money makes us poorer. Moreover, that's the kind of world we have been living in for the past several years, which means that it is a kind of world that students should understand. […] Depression economics is marked by paradoxes, in which seemingly virtuous actions have perverse, harmful effects. Two paradoxes in particular stand out: the , in which the attempt to save more actually leads to the nation as a whole saving less, and the less-well-known , in which the willingness of workers to protect their jobs by accepting lower wages actually reduces total employment. […] In times of depression, the rules are different. Conventionally sound policy—s, a firm commitment to —helps to keep the economy depressed. Once again, this is not normal. Most of the time we are not in a depression. But sometimes we are—and 2013, when this chapter was written, was one of those times.

Because the Trump team insisted that a roaring recovery was coming, and refused to notice that it wasn’t happening, we’ve now stumbled into a completely gratuitous economic crisis.