The ruble, the national currency of Russia, has been depreciating the whole week. At midday on Friday, the dollar was trading at 83 rubles, the euro — 91 rubles. These are the lowest values that the ruble has hit since last spring when Russia’s invasion of Ukraine was just beginning. At the time, the currency markets were in full-blown panic, the dollar soared to 130 rubles, while the exchange rate fluctuations reached 10% a day. There are now far fewer causes for worry. Following the OPEC+ decision to cut oil production, the Brent crude price rose to $85, a comfortable...