following the latest set of extraordinary measures by the European Central Bank designed to stimulate the Eurozone economy.

It will buy corporate bonds, the sort of direct lending to companies the U.S. Federal Reserve was forced to try during the Great Depression of the 1930s.

Interest rates have been pushed into negative territory, and significant portions of the bonds market also trade below zero.

And yet, the continent's currency has been getting stronger.

Perhaps the best view to have of any one currency at any one point in time is ignorance,

or at least deference to the Gods of Money who inhabit markets too deep and ineffable to fathom.

Yet the ECB's in good company.

It is one of five central banks which have announced looser monetary policy measures this year,

looser than many of the investors and economists who tried to predict these things had forecast.

Loose monetary policy might be thought to be associated with weaker currencies,

but Japan, New Zealand, Sweden and Norway have all seen the value of their currency rise following the announcements of fresh stimulus,

a sign that markets are losing faith in the powers of central banks, perhaps.

One way to think about these moves, maybe to take a longer-term view.

The recent strengthening of the yen seems strange until we look at where it's trading only a few years ago.

It remains extremely weak compare to what a yen was worth in 2012.

The average rate against the dollar this century is 106 yen to the dollar, not far from the 109 where it was trading on Tuesday.

Think about the euro in similar terms, and as you can see from this chart,

the question is which is the right level for the currency.

Here, where it has traded recently, or here, the much stronger level where it traded before 2014.

If the century average of €1.23 to the dollar is anything to go by, the euro could easily be stronger than it is today.

There is also another reason to think that the euro could strengthen.

Monetary policy, as judged by real interest rates, is perhaps looser in the U.S. than it is in Europe.

If you consider this chart,

real interest rates are calculated by subtracting the rate of inflation from nominal interest rates.

BNP Paribas here have compared real rates in Europe and the U.S., where inflation has started to pick up,

pushing negative rates lower, the negative real rates lower.

The euro, they argue, could strengthen further in the next few months.

If it does, cheaper imports would mean even less inflation in Europe,

putting further pressure on the ECB to act,

but also raising fresh questions about its power if it does.