How is your knowledge of the 1929 Wall Street Crash and the Great Depression that followed it in the 1930s?

Not so good? Don’t worry, you’re not alone. But this is likely to be one of the world’s biggest talking points in coming months and years.

I was reminded of the Depression yesterday by the appearance of one of the legendary names from that distant era in the rescue of U.S. bank Bear Stearns.

J.P. Morgan was the renowned banker called on by the President to sort out the financial mess during one of the slumps of the period. Morgan set about systematically weeding out the companies that should be allowed to go to the wall, and those that were too important to allow to fail.

Yesterday the old feller’s bank, JP Morgan Chase and the New York Federal Reserve combined to stuff funds back into failing giant Bear Stearns, brought low by the gathering credit crunch.

The problem this time around is one of leverage and its effects on banks’ lending ratios — the multiple of lending to capital reserves a financial institution is allowed to build up by the authorities. The Geneva standard is that a bank’s capital must not fall below 8 percent of its lending. That number has been around a long time — I remember it from Alfred Marshall’s ancient classic textbook on economics during my university days.

Eight percent represents a ratio of 12.5 of lending to capital. These days it’s the norm for private equity companies to leverage many times more than that — supported by banks, of course, which then calculate their capital on a hugely inflated valuation for partly subprime debt. When the bubble bursts — as is now happening — both sides of the deal collapse.

Recently-bust Carlyle Capital Corporation (CCC) leveraged its equity 32 times to finance a $21.7bn portfolio of residential mortgage-backed securities issued by Freddie Mac and Fannie Mae. These instruments were financed by some of the biggest names in world banking.

With the housing market going south with a vengeance, it’s said that many banks’ capital reserves to lending ratios have slipped close to zero. The global financial system is floating on a cushion of fresh air.

There are always the consolations of philosophy for us to fall back on. Not the nitpicking academic variety which parses the meaning of words to death, but the active philosophy of Socrates whose adage, “The unexamined life is not worth living” should be a talisman of the financial sector.

In Britain, Gordon Brown’s Financial Services Authority (FSA), set up by him ten years ago to police the financial markets and the banks, completely missed the Northern Rock collapse, which was due to the bank raising money solely on the money markets and bundling the debts — many subprime — into packages and selling the risk on. When the money markets dried up, the bank had nowhere to go but to the Government to bail it out and eventually to nationalize it.

“The unexamined life is not worth living”. It seems the FSA did not examine the fifth largest bank in the UK, or spot the snake oil splashing around its floors.

Now consider what happened next as an example of both hubris and the reverse of Socrates’s dictum. Brown is calling for a “global financial watchdog” to perform for the entire planet what his FSA did for Britain.

Self-knowledge where art thou? The man has the richest fantasy life since Walt Disney.

Since we can’t have financial stability, or even politicians who examine their actions carefully, we must fall back on the real consolations of philosophy — everything changes and nothing remains the same.

Except death and taxes, of course.