It’s one of the first rules in the book of mainstream economic wisdom: a country’s economy is the thermometer which “reads” its stock market’s temperature. If financial conditions are heating up, stocks rise; if they are cooling down, stocks fall. Were it so simple — millionaires wouldn’t make up a measly .15% of the global population.

Obviously, there’s a major flaw with this logic; namely, it isn’t true. Time and again, stock prices smolder to near boiling even as economic growth chills to the bone. (The opposite also holds: Stock prices cool down even as the economy is on fire.)

Take, for instance, Germany’s main stock index, the DAX 30. On August 13, Europe’s number one economy reported a .3% rise in gross domestic product (GDP) — Germany’s first quarter of growth since January 2008. Soon after, the …