Back in the fall, former Federal Reserve Chairman Alan Greenspan stirred things up by making some public statements about the importance of gold, calling it “the premier currency, where no fiat currency, including the dollar, can match it…” Greenspan also indicated that he believes the Fed's balance sheet will eventually catch fire and ignite some serious inflation. A good reason, he argued, to buy gold.

Well, now Greenspan is back in the news throwing a “wet blanket” on hopes for u.s. growth, as Bloomberg puts it.

The United States is doing better than anybody else, but we're still not doing all that well… We still have a very sluggish economy.”

“Almost all of the weakness in the last four, five, six years has been in long-lived investments… Until these pick up, we're not going to get the kind of vibrant growth that everyone is hoping for.”

These are just a sample of Greenspan's comments to Bloomberg. He also does not have confidence that anyone can forecast the price of oil in 2015, because the market hasn't stabilized yet.

So what is the takeaway for long-term investors trying to position themselves in the big picture of the world's economy? You'll want to read Greenspan's article in the journal of Foreign Affairs published back in September. To Greenspan, there is little question that gold and China will play a central role in the years to come.

If China were to convert a relatively modest part of its $4 trillion foreign exchange reserves into gold, the country's currency could take on unexpected strength in today's international financial system. It would be a gamble, of course, for China to use part of its reserves to buy enough gold bullion to displace the United States from its position as the world's largest holder of monetary gold. (As of spring 2014, U.S. holdings amounted to $328 billion.) But the penalty for being wrong, in terms of lost interest and the cost of storage, would be modest. For the rest of the world, gold prices would certainly rise, but only during the period of accumulation. They would likely fall back once China reached its goal.

“The broader issue — a return to the gold standard in any form — is nowhere on anybody's horizon. It has few supporters in today's virtually universal embrace of fiat currencies and floating exchange rates. Yet gold has special properties that no other currency, with the possible exception of silver, can claim. For more than two millennia, gold has had virtually unquestioned acceptance as payment. It has never required the credit guarantee of a third party. No questions are raised when gold or direct claims to gold are offered in payment of an obligation; it was the only form of payment, for example, that exporters to Germany would accept as World War II was drawing to a close. Today, the acceptance of fiat money — currency not backed by an asset of intrinsic value — rests on the credit guarantee of sovereign nations endowed with effective taxing power, a guarantee that in crisis conditions has not always matched the universal acceptability of gold.”