How do you know a major financial crisis is coming? Look for a spike in privately held debt, by households and corporations.

That’s the argument of Richard Vague, author of The Next Economic Disaster: Why It’s Coming and How to Avoid It. Having worked for more than 30 years in consumer banking, Vague describes how he saw the build-up of private debt in the mortgage and credit card industries first hand—even though it’s an issue that neoclassical economists like Milton Friedman barely acknowledge. To avoid another crisis, Vague says firms and governments need to take debt forgiveness—the biblical “jubilee”—seriously. As he says, after the financial crisis “We helped the banks, we didn’t help the households.