The circular arch, which the Spaniards claim to have received from the East at least five centuries before the invasion of the Moors, and which is supposed to have had its origin in the bending of twigs and branches, differs somewhat from the genuine Moorish arch, its curves being less pronounced. The earliest example of the Mussalman arch is thought to be that of the Grand Mosque of Cairuan.[106] It is extremely interesting to trace the changes through which this Spanish Mussalman arch passed during the four centuries of Moorish supremacy in the Peninsula. Those of my readers who have watched the evening sun gradually disappear behind the horizon of the sea, can easily picture to themselves the curves of this arch in its early stages. As the golden ball first dips itself, as it were, into the water, its outline forms a circular arch; but one which is neither the Roman arch nor the later horseshoe arch, but what may be called the _archaic circular arch_. Then, as it dips deeper and deeper, the curves gradually disappear, till exactly half of the ball is hidden: at that moment the outline is that of what is usually styled _a Roman arch_ (early Norman). About the beginning of the eleventh century, Moorish architecture showed a tendency to lengthen the curves of its circular arch, and at the same time began to make it pointed instead of circular. That is to say, the circular arch and the pointed arch were fused into a new kind of arch, a _pointed horseshoe arch_. It is the first of these, the _archaic_ circular arch, which we find on the pagan tombstones of the second century preserved in various Spanish museums, which we find traced in the illumination of ancient Spanish parchments, which we find in the bridge over the river Cubillas, and, finally, which we find in the extremely rare relics of Visigothic architecture, of which two of the most interesting are in the province of Galicia.[107] The foreigners who have devoted the most careful study to Spanish architecture are the French; but they have all without exception approached the subject with the preconceived idea that all the best architecture in Spain is the work of French architects; and, under this unfortunate delusion, they have misled almost every one, even Spaniards! Street is still the best English authority on Spanish architecture, though, of course, his work is somewhat antiquated;[108] but he saw comparatively little--too little to enable him to be a competent judge of Spanish national art. The Moorish architects who constructed the Great Mosque at Cordova, as we see it to-day, adopted and improved the style of architecture which the Visigothic Christians had employed there before their arrival. It must be remembered that the Visigoths were the most cultured of all the barbarians of the north, and they were Arians long before they became Roman Catholics.