But that nothing should be lost to western art, the Byzantine Romanesque was made to sweep most widely over the old world, and enter Europe at the remotest point. "On the wings of Mohammed's spreading creed," says Hope, "wafted from land to land by the boundless conquest of his followers, the architecture of Constantinople, extending one way to the furthest extremities of India, and the other to the utmost outskirts of Spain, prevailed throughout the whole of the regions intervening between the Ganges and the Guadalquiver; in every one of the different tracks into which it was imported, still equally different from the aborigines, or early possessors. Thus, while in none of the various and distant countries, we observe previous to the adoption of Islamism the slightest approach to those inventions, the pride and the stay of architecture--the arch and the cupola; in all of them alike, on the very first settling in them of the Mohammedans, we see these noble features immediately appearing, from the application of Greek skill, in the full maturity of form they had attained among themselves." Leaving the Saracenic Romanesque to return by Sicily and Spain into southern France, and thence to ascend the height of mediæval culmination, let us proceed in the grand central track of Teutonic art. The Rhine is the great channel of modern civilization, and near its banks are the clearest indications of progressive art. The original cathedral at Treves was built by the pious mother of Constantine, and seems, like the cotemporary church at Jerusalem, to have consisted of two distinct edifices, one circular, the other square. These two forms entered into diversified combinations thenceforth, and ever constituted the peculiarity of German architecture. The tenth and eleventh centuries afford many curious specimens which are important in the history of art. Such are the cathedrals of Spire, Worms, Mayence, and others yet extant, and which attest extraordinary solidity and magnificence. The western apse of the cathedral at Mayence is perhaps the only example in Germany where a triapsal arrangement has been attempted with polygonal instead of circular forms. Surely a new type of art is near. At this point, too, we have witnessed enough of progressive spire-growth in Germany to believe that the origin of that aspiring member lies amid the towers which cluster so copiously on the churches by the Rhine, and especially the beautiful group of indigenous art at Cologne.