It was an element in this sublime and yet sinister simplicity of Islam that it knew no boundaries. Its very home was homeless. For it was born in a sandy waste among nomads, and it went everywhere because it came from nowhere. But in the Saracens of the early Middle Ages this nomadic quality in Islam was masked by a high civilization, more scientific if less creatively artistic than that of contemporary Christendom. The Moslem monotheism was, or appeared to be, the more rationalist religion of the two. This rootless refinement was characteristically advanced in abstract things, of which a memory remains in the very name of algebra. In comparison the Christian civilization was still largely instinctive, but its instincts were very strong and very much the other way. It was full of local affections, which found form in that system of _fences_ which runs like a pattern through everything mediaeval, from heraldry to the holding of land. There was a shape and colour in all their customs and statutes which can be seen in all their tabards and escutcheons; something at once strict and gay. This is not a departure from the interest in external things, but rather a part of it. The very welcome they would often give to a stranger from beyond the wall was a recognition of the wall. Those who think their own life all-sufficient do not see its limit as a wall, but as the end of the world. The Chinese called the white man "a sky-breaker." The mediaeval spirit loved its part in life as a part, not a whole; its charter for it came from something else. There is a joke about a Benedictine monk who used the common grace of _Benedictus benedicat_, whereupon the unlettered Franciscan triumphantly retorted _Franciscus Franciscat_. It is something of a parable of mediaeval history; for if there were a verb Franciscare it would be an approximate description of what St. Francis afterwards did. But that more individual mysticism was only approaching its birth, and _Benedictus benedicat_ is very precisely the motto of the earliest mediaevalism. I mean that everything is blessed from beyond, by something which has in its turn been blessed from beyond again; only the blessed bless. But the point which is the clue to the Crusades is this: that for them the beyond was not the infinite, as in a modern religion. Every beyond was a place. The mystery of locality, with all its hold on the human heart, was as much present in the most ethereal things of Christendom as it was absent from the most practical things of Islam. England would derive a thing from France, France from Italy, Italy from Greece, Greece from Palestine, Palestine from Paradise. It was not merely that a yeoman of Kent would have his house hallowed by the priest of the parish church, which was confirmed by Canterbury, which was confirmed by Rome. Rome herself did not worship herself, as in the pagan age. Rome herself looked eastward to the mysterious cradle of her