A valueless banking boom?
So how big has been the recent boom in some parts of the banking industry?
Big enough, according to new figures released this morning by the Bank for International Settlements (the central bankers' central bank, as if you didn't know) and the Bank England.
According to the results of their latest triennial survey, global foreign exchange turnover rose 20% to $4trn per day on average (yes, that's each single day) in April 2010 compared with April 2007.
Or to put it another way, a sum equivalent to the entire output of the global economy is traded around once a fortnight on currency markets.
What's more, London's portion of this business has increased even faster, by 25%, so UK based banks' share of forex business is a market-leading 37%.
So no evidence as yet that the reality and threat of horrid new bank taxes and heinous regulation has seriously damaged UK based banks.
As for over-the-counter interest rate derivatives (transactions that are largely bets on the direction of interest rates), these rose 24% globally to $2.1 trn.
And Britain's share of these trades was a striking 46%, up from 44% in 2007.
I presume that warms your patriotic cockles.
What is there to say about an industry that deals in numbers that boggle the typical human brain?
Well, the first thing to point out is that a tiny fraction of this business is carried out on behalf of "non-financial" businesses - or what some would describe as "real" companies (you know the sort of thing I mean - businesses that make cars, or create music, or sell advertising, rather than trading in dematerialised, electronic money on a screen).
These non-financial companies were responsible for just 13% of forex transactions, their lowest proportion for 12 years.
By contrast, "other" financial institutions - such as hedge funds, insurers, mutual funds and so on - contributed a record 48% of the business.
And there's a similar story on the origination of these massive flows of money in the OTC interest rate derivative business.
What does that mean?
Well some would view these statistics as evidence that the banking industry has become more than slightly detached from the "real" economy, that many of its activities are either pure speculation, or attempts to hedge speculation, or attempts to hedge the hedges.
Also, it would be pretty difficult to argue that the net effect of all this financial business has been to reduce the volatility of markets, or to improve the stability of the global economy, or to increase the growth rate of the global economy.
Many might well dispute that the great banking meltdown of 2008 happened because of this explosive growth in financial trading - but the trading certainly didn't prevent the crash.
And there is a massive disconnect between a global economy that has less than doubled in size over 12 years and - on the other hand - OTC derivative transactions that have increased eight fold while foreign exchange transactions have almost trebled in value.
What's more, as I've pointed out before, the global economy was growing quite as fast in the 1960s when much of this financial business barely existed.
So those who can't see the point of all these financial trades may (ahem) have a point - unless, that is, you believe the enrichment of financial traders and hedge fund managers is a social good in itself.
Which is why, some would say, it's slightly odd that when no less an authority than the chairman of the Financial Services Authority, Lord Turner, questions the social utility of much activity in financial markets, and also suggests that it might be no bad thing to levy a tiny Tobin tax on all this frenetic trading in electrons, well it's curious that the chancellor of the exchequer (who could use a bob or two) doesn't lick his chops and demand a bit of that.