Once before, East and West have met and merged. On the plains where the soldiers of Darius and Alexander slaughtered one another, and where the Macedonian phalanxes recoiled before the castellated elephants of Porus, a marriage was consummated. Hovering over the heads of the opposing armies, the angel of Europe and the angel of Asia embraced, and sent their lifebloods coursing through each other. Passage was made to India. The two continents slowly faced about. Two reservoirs that had been accumulating for eons the precious distillations of two great centers of the human race began mingling their essences. In whatever the East did, there was evident the hand of the West. In whatever the West thought there was visible the prismatic intelligence of the East. The gods of Greece showed their smooth foreheads on the banks of the Ganges. Oriental systems refracted the blonde Mediterranean light into an hundred subtle tints. But the empire of Alexander crumbled, Parthians annihilated the legions of Crassus. Persians and Seljuks and Ottomans barred Europe from the East. Steady communication ceased. Asia withdrew under her cloudy mysterious curtains. Legendary fumes, Cathay, Zipango, the Indias of the Great Ocean, arose. Once again, the two basins were cut off. Once again, each began secreting a substance radically different from the other's, a substance growing more individual with each elapsing century. For almost two thousand years, East and West developed away one from the other.