Nationalism is always an effort in a direction opposite to that of the principle which creates nations. The former is exclusive in tendency, the latter inclusive. In periods of consolidation, nationalism has a positive value, and is a lofty standard. But in Europe everything is more than consolidated, and nationalism is nothing but a mania, a pretext to escape from the necessity of inventing something new, some great enterprise.

Chapter XIV: Who Rules The World? - The Revolt of the Masses (1929)