AFTER six months of war the riddle is still the same: Can the Allies defeat Nazi Germany by their blockade, or can she become self-supporting in safety behind the Siegfried Line? Strategists and statisticians are busy checking and rechecking the facts and estimating the potentialities. Nobody can prove what the final issue will be. But one can ascertain the range of probabilities. At first sight it seems as though history were repeating itself in a cycle of only twenty-five years. Again Great Britain and France are fighting Germany on the Western Front; again they are trying to throttle her by a naval blockade; again Mitteleuropa is in the German grasp. But at closer range the contours look different. In 1914 the war came as a surprise after an era of forty-four years of peace. A large accumulation of invisible reserves was ready for mobilization by both sides when the struggle began. This time, though Nazi Germany has built up and is operating a highly perfected totalitarian fortress economy, she lacks the dormant reserves normally carried over from a long era of peace. Further, Alsace-Lorraine, Belgium and northern France are not, this time, in her hands. Even the Saar coal and iron region lies almost idle, within range of the Maginot Line guns. Offsetting these disadvantages, the whole German machinery of planning, rationing and requisitioning became fully operative from the first day of war. This happened last time only after the war had been going on for two years. Our conclusion must be that although Germany is weaker today in economic assets than she was in 1914, she is relatively stronger in utilizing them. Her substance is smaller, but her effective exploitation of it is greater.