This week we do some review on a very important topic, the velocity of money. If we don't understand the basics, it is hard to make sense of the hash that our world economy is in, much less understand where we are headed.

But before we jump into that, I want to let my Conversations subscribers know that we have posted a recent conversation with two hedge-fund managers, Kyle Bass of Hayman Advisors [and his staff] here in Dallas and Hugh Hendry of the Eclectica Fund in London. Our discussions centered on what we all think has the potential to be the next Greece, but on a far more serious level. It was a fascinating time.

Then next Wednesday we will post a Conversation I had with George Friedman of Stratfor fame, and then the following Wednesday a Conversation that I just completed with Dr. Ken Rogoff and Dr. Carmen Reinhart, the authors of This Time Is Different.

For new readers, Conversations with John Mauldin is my one subscription service. While this letter will always be free, we have created a way for you to "listen in" on my conversations with some of my friends, many of whom you will recognize and some whom you will want to know after you hear our conversations. Basically, I will call one or two friends each month and, just as we do at dinner or at meetings, we will talk about the issues of the day, with back and forth, give and take, and friendly debate. I think you will find it very enlightening and thought-provoking and a real contribution to your education as an investor.

And as you can see, I can get some rather interesting people to come to the table. Current subscribers can renew for a deeply discounted $129, and we will extend that price to new subscribers as well. To learn more, go to http://www.johnmauldin.com/newsletters2.html. Click on the Subscribe button, and join me and my friends for some very interesting Conversations.

This week we look at the second half of my speech from a few weeks ago at my annual Strategic Investment Conference in La Jolla. If you have not read the first part, you can review it here. The first few paragraphs are a repeat from last week, to give us some context. Please note that this is somewhat edited from the original, and I have added a few ideas. You can also go there to sign up to get this letter sent to you free each week.

Okay, when you become a central banker, you are taken into a back room and they do a DNA change on you. You are henceforth and forever genetically incapable of allowing deflation on your watch. It becomes the first and foremost thought on your mind: deflation, we can't have it.

MV=PQ. This is an important equation, right up there with E=MC2. M (money or the supply of money) times V (velocity -- which is how fast the money goes through the system -- if you have seven kids it goes faster than if you have one) is equal to P (the price of money in terms of inflation or deflation) times Q (roughly standing for the Quantity of production, or GDP)

So what happens is, if we increase the supply of money and velocity stays the same, and if GDP does not grow, that means we'll have inflation, because this equation always balances. But if you reduce velocity (which is happening today) and if you don't increase the supply of money, you are going to see deflation. We are watching, for reasons we'll get into in a minute, the velocity of money slow. People are getting nervous, they are not borrowing as much, either because they can't or the animal spirits that Keynes talked about are not quite there.

"A severe global recession will lead to deflationary pressures. Falling demand will lead to lower inflation as companies cut prices to reduce excess inventory. Slack in labour markets from rising unemployment will control labor costs and wage growth. Further slack in commodity markets as prices fall will lead to sharply lower inflation. Thus inflation in advanced economies will fall towards the 1 per cent level that leads to concerns about deflation.

"Deflation is dangerous as it leads to a liquidity trap, a deflation trap and a debt deflation trap: nominal policy rates cannot fall below zero and thus monetary policy becomes ineffective. We are already in this liquidity trap since the Fed funds target rate is still 1 per cent but the effective one is close to zero as the Federal Reserve has flooded the financial system with liquidity; and by early 2009 the target Fed funds rate will formally hit 0 per cent. Also, in deflation the fall in prices means the real cost of capital is high - despite policy rates close to zero - leading to further falls in consumption and investment. This fall in demand and prices leads to a vicious circle: incomes and jobs are cut, leading to further falls in demand and prices (a deflation trap); and the real value of nominal debts rises (a debt deflation trap) making debtors' problems more severe and leading to a rising risk of corporate and household defaults that will exacerbate credit losses of financial institutions."

- Professor Nouriel Roubini of New York University

The late and great Milton Friedman told us that inflation is always and everywhere a monetary phenomenon. But there is an asterisk to his equation that we need to examine, namely, the velocity of money. Sometimes a fast-growing money supply is not as inflationary as you might think. Then we will take quick looks at why the banking sector is in for more and larger rounds of write-offs, as well as note that the housing industry is in a hole but is gamely digging itself deeper. This week's letter will require you to put your thinking cap on as we travel to a mythical island to get an understanding of how the economy really works. There are a lot of charts, so the letter may again print long, but the word length is normal. And with no "but first," we jump right in.

When most of us think of the velocity of money, we think of how fast it goes through our hands. I know at the Mauldin household, with seven kids, it seems like something is always coming up. And with my oldest daughter Tiffani getting married this summer (forget gas, you haven't seen inflation until you start buying floral arrangements), more kids in school, "Dad, I need a car," high energy costs, etc., the velocity, at least in terms of how fast money seems to go out the door, seems faster than normal. And what about my business? Travel costs are way, way up, and as aggressive as we are on the budget, expenses seem to rise. About the only way to deal with it is, as my old partner from the 1970's Don Moore used to say, is to make it up with "excess profits," whatever those are.