Gold is in the middle of what looks like an unstoppable bull run. It has already punched through $4,000 an ounce. At the rate the price is rising, it may well go to $5,000 within a few weeks, and perhaps even $6,000 as the next year unfolds. There have been lots of different explanations for this, from the looming collapse of the dollar, to secret Chinese buying, to the conspiracy theories circulating on the wilder fringes of the internet, such a secret plot to re-establish the gold standard, or attempts to replace all the metal that is meant to be...