Comparisons have often been drawn, and with good reason, 1 between the history of Italy in the fourteenth and fifteenth centuries after Christ, and that of Ancient Greece in the fourth and third centuries before Christ. In each a group of vigorous but quarrelsome city states had in the preceding century beaten off a long-protracted attack by an external power, which they regarded as “barbarous.” The Lombard League and the Papacy had finally defeated the attempt of the Hohenstaufen emperors to reduce Italy; the united Greeks had turned back the Persian kings, after the thirty years of threatened invasion, by the victories of Plataea and Mycale. If a further analogy in detail is wanted, Persia had been helped, for reasons of petty inter-state jealousy, by great Greek cities like Thebes, while others (like Argos) had kept out of the game. So in Italy cities like Lodi or Como or Pisa had backed the Emperor consistently, because they hated Milan or Florence just as Thebes hated Athens, and others had failed to give any effective support to the Guelf cause.