To know is not too demanding: it merely requires memory and time. But to understand is quite a different matter: it requires intellectual ability and training, a self conscious awareness of what one is doing, experience in techniques of analysis and synthesis, and above all, perspective.

It is also in theory, conceivable that some universal empire some day might cover the whole globe, leaving no external "barbarians" to serve as invaders.

The failure of Christianity in the areas west from Sicily was even greater, and was increased by the spread of Arab outlooks and influence to that area, and especially to Spain.

After years of work in both areas of study, I concluded that the social sciences were different, in many important ways, from the natural sciences, but that the same scientific methods were applicable in both areas, and, indeed, that no very useful work could be done in either area except by scientific methods.

To this day the Arab influence is evident in southern Italy, northern Africa and, above all, in Spain.

A community is made up of intimate relationships among diversified types of individuals--a kinship group, a local group, a neighborhood, a village, a large family.

Western civilization presents one of the most difficult tasks for historical analysis, because it is not yet finished, because we are a part of it and lack perspective, and because it presents considerable variation from our pattern of historical change.