And still the revelations come. Leading banks pay yet more record fines for egregious behaviour ranging from sanctions-busting to facilitating tax evasion. Their involvement in rigging markets now extends beyond Libor, the rate at which banks lend to each other, to foreign exchange and the gold market. It appears to be a pervasive rather than occasional phenomenon. Even when they have been shopped, they do not give up. UK banks, we discover, have been underpaying compensation for mis-sold payment protection insurance.

All this corporate wrongdoing is combined with immense personal enrichment and a paucity of prosecutions of people at the top. How are we to make sense of this bizarre concatenation of events, in which the financial system appears to have become an ethics-free zone?

One fruitful way to look at it is to think of the financial system as having, at any given moment, a stock of moral capital. This complements an insight of economist John Kenneth Galbraith. In his book on the 1929 crash he argued that there is always an inventory of undiscovered embezzlement, which he called the “bezzle” – in other words, negative moral capital. When markets ride high the bezzle increases. Come the recession people become more suspicious, audits become more penetrating and the bezzle shrinks.