Built to Fail: Key Lessons from the Financial Crisis

"The ability to sustain high rates of economic growth, decreed by governments and central bankers, is questionable. The aggressive increase in debt globally resulted in a sharp increase in sustainable growth rates, wherein $4 to $5 of debt was required to create $1 of growth. Approximately half the recorded growth in the US over recent years was driven by borrowing against the rising value of houses (mortgage equity withdrawals). As the level of debt in the global economy decreases, attainable growth levels also decline."