The biggest threat to advanced economies is that debt will accumulate until the overhang weighs on growth.

If there is one common theme to the vast range of crises...it is that excessive debt accumulation, whether it be by the government, banks, corporations, or consumers, often poses greater systemic risks than it seems during a boom.

The essence of the this-time-is-different syndrome is...rooted in the firmly held belief that financial crises are things that happen to other people in other countries at other times; crises do not happen to us, here and now. We are doing things better, we are smarter, we have learned from past mistakes. The old rules of valuation no longer apply. Unfortunately, a highly leveraged economy can unwittingly be sitting with its back at the edge of a financial cliff for many years before chance and circumstance provoke a crisis of confidence that pushes it off.

The biggest threat to advanced economies is that debt will accumulate until the overhang weighs on growth.

Perhaps more than anything else, failure to recognize the precariousness and fickleness of confidence - especially in cases in which large short-term debts need to be rolled over continuously - is the key factor that gives rise to the this-time-is-different syndrome. Highly indebted governments, banks, or corporations can seem to be merrily rolling along for an extended period, when bang! - confidence collapses, lenders disappear, and a crisis hits.