Where the first diagonal-crossing ribs are to be found will probably never be known. Various have been the claimants. The Rhenish claim is no longer taken seriously. Gothic made its first appearance in Germany as a fully developed French art, and its XIII-century name, there, was _opus francigenum_. In his Gothic work the Teuton showed a fondness for the _tour-de-force_ and his manual dexterity surprises more than it satisfies. The best German works in architecture are the sober Romanesque churches. Germany's school was developed a century before the Romanesque of France; across the Rhine occurred no Norman invasion to sever art traditions from Charlemagne's renaissance. The pre-Gothic art suited her ethnical temperament, and was long adhered to. While France was building Gothic, Germany was still erecting Romanesque cathedrals. Not till the end of the XII century were churches along that "_rue des moines_," the Rhine, vaulted in the new manner. The claim of Italy to be the first to use the diagonal ribs is denied by most French archæologists, but is put forward by the Italian scholar Rivoira and by Mr. Arthur Kingsley Porter.[12] The latter cites the church of Sannazzaro Sesia as showing proofs that its high nave was Gothic vaulted by 1040. For a century, he says, the Lombard churches used diagonals, especially in Milan, where wood was scarce and it was easier to build permanent brick ribs under the groin vault than to mold the groin on a temporary substructure. Diagonal ribs were invented, he thinks, as a device to economize wood. That may be true of the Lombard churches, of which he has made an elaborate study. And it may be true that the use of such diagonals filtered into Provence and Languedoc, where appeared some early Gothic vaults sporadically before 1150, at Fréjus, Marseilles, Maguelonne, and Moissac, all with the rectangular profile of the Lombard type. The theory he advocates does not prove why the Ile-de-France masons could not themselves, without hint from Lombardy, have stumbled on the new feature which was to revolutionize the builder's art. Why should we prefer his explanation for the first use of diagonals--the desire to economize wood--to that advanced by the French scholars--the effort to brace a falling groin vault?