With the upper basin of the Rhône this study has little to do. The lower Rhône country enters into our story, although not as the main theatre in which its events took place. We are mainly concerned with the upper Garonne basin, the strip of Mediterranean coastal plain curving from the lower Rhône to the Pyrenees, the mountain slopes which border upon these two regions and the passage, or gap, of Carcassonne which connects them. For in that space (roughly of a hundred by a little over a hundred and fifty English miles) was decided the failure of the first attempt to break the moral unity of mediæval Christendom. And in that struggle the Inquisition for the first time definitely appears. Even this small stretch of country presents great differences of climate and of appearance. The landscape of the coastal plain between the Rhône and the Pyrenees is of the typical Mediterranean sort which hardly changes all around the inland sea. The sea itself is intensely blue and the boats upon it are rigged with slim lateen sails pointed like sharks’ fins. Within sight of the sea are mountains, great stark masses of rock like the bare bones of the world. No forests, but between the sea and the mountains extends a strip of land systematically cultivated down to its last square inch, showing everywhere the vine and the olive, and built up in terraces wherever there is a slope. This strip of land is always narrow—from the town of Beziers, for instance, both mountains and sea are full in sight. When rain falls it comes down fiercely as it does in America, unlike the gentle misty rains of England and Northern France. Usually the air is so clear that all outlines come out sharp and strong—one thinks of the trenchant Latin phrase and the fixed lines of classic columns. The sun is dazzling and powerful, and the roads are full of white dust. The houses are of stone, flat topped or nearly so, and generally roofed in red tile. The people, as befits the heirs of an immemorial and still vigorous civilization, are loud-voiced, vivacious in gesture, ceremonious in compliment, and both easy and dignified in repose. Westward from Narbonne, a sharply defined valley, deep and regular like a vast trench, seems to open a path toward the Atlantic. A man going east or west is held to this valley; to leave it is to be caught in the deep irregular gorges of the Montagne Noire (which is the southernmost outlier of the Cévennes) to the north of the valley, or in the equally hopeless gorges of the Corbières (which are the north-eastern outliers of the Pyrenees) to the south of it. This valley culminates in what may be called the gap of Carcassonne, for in the neighbourhood of that town it is deepest and most clearly marked, although the actual water parting between the Atlantic and the Mediterranean is somewhat to the west.