_CHAPTER IV_ _ARAGON_ _a._ _The Atom_ _b._ _The Way of the Atom_ _a._ _The Atom_ From the Mediterranean to the Atlantic, the north boundary of Spain is mountain. To the east it is called the Pyrenees: a wall of snowy rock that falls, save for a space above the fertile fields of Catalonia, into the desert of Aragon and Navarre. Westward, the wall is lower and has another name: Cantábrico. It too is wild, but the more moderate moisture covers it with pine and its fall southward is but a step to the high meseta of León and Castile. Within this barrier that like a jagged knife cuts Spain from Europe lived the Christian Remnant before the Arabs. And from two fastnesses of this wall--where the Arabs never gained a foothold--went forth at once the _Reconquista_ which for eight hundred years, thrusting, expanding, retreating, made war upon the Moslem and at last after innumerable shifts of fortune drove him out. The western point of the Reconquest’s birth lies in the perpendicular rocks of the Asturias. This is the cradle of the Kingdom of León, which, thrusting from the Cantábrico, became Castile. To the east, the nucleus of the long “push” south was in the bleakest and highest Pyrenees of Spain: the Ribagorza and Sobrarbe whose hard squat Iberian chieftains were the first kings of Aragon. Not till the last decades of the fifteenth century, at the end of the long battle, did the two Christian forces join and become Spain. During seven hundred years, they had waged war against Mohammed; they had grown great in Spain; they had flung their power northward across the mountains, eastward across the sea to Italy and Greece: but they had lived--Castile and Aragon--separate from each other and for the most part hostile. Within the Pyrenees--the stratified chaos north of Huesca and Barbastro--the atom of Aragon lives above the splendor it has given forth. Here, if anywhere, is the aboriginal Spaniard--unchanged as his mountains. The Iberians who were pushed north from the desert or south from Acquitaine into the Sobrarbe and the Ribagorza found themselves in a sort of Continental crow’s-nest, high above invasion. The Romans did not tarry here, nor the Visigoths. The Arabs were beaten back, south of Jaca, and had to veer to the east to enter France. For countless ages, these primeval men beside the river Aragon lived uninvaded, until their atomic energy grew to be explosive and they became invaders.