Here is a march or boundary between two things, the one familiar to most English travellers, the other unfamiliar. The familiar thing is the rich alluvium and gravel of the Northern French countrysides, the poplar trees, the full and quiet rivers, the many towns and villages of stone, the broad white roads interminable and intersecting the very fat of prosperity, and over it all a mild air. The unfamiliar is the mass of the Avernian Mountains, which mass is the core and centre of Gaul and of Gaulish history, and of the unseen power that lies behind the whole of that business. The plains are before one, the mountains behind one, and one stands in that borderland. I know it well. I have said that in the Avernian Mountains was the centre of Gaul and the power upon which the history of Gaul depends. Upon the Margeride, which is one of their uttermost ridges, du Guesclin was wounded to death. One may see the huge stones piled up on the place where he fell. In the heart of those mountains, at Puy, religion has effects that are eerie; it uses odd high peaks for shrines--needles of rock; and a long way off all round is a circle of hills of a black-blue in the distance, and they and the rivers have magical names--the river Red Cap and Chaise Dieu, "God's Chair." In these mountains Julius Caesar lost (the story says) his sword; and in these mountains the Roman armies were staved off by the Avernians. They are as full of wonder as anything in Europe can be, and they are complicated and tumbled all about, so that those who travel in them with difficulty remember where they have been, unless indeed they have that general eye for a countryside which is rare nowadays among men. Just at the place where the mountain land and the plain land meet, where the shallow valleys get rounder and less abrupt, I went last September, following the directions of a soldier who had told me how I might find where the centre of the manoeuvres lay. The manoeuvres, attempting to reproduce the conditions of war, made a drifting scheme of men upon either side of the River Sioule. One could never be certain where one would find the guns. I had come up off the main road from Vichy, walking vaguely towards the sound of the firing. It was unfamiliar. The old and terrible rumble has been lost for a generation; even the plain noise of the field-piece which used to be called "90" is forgotten by the young men now. The new little guns pop and ring. And when you are walking towards them from a long way off you do not seem to be marching towards anything great, but rather towards something clever. Nevertheless it is as easy to-day as ever it was to walk towards the sound of cannon.