The backwardness of our religious and social developments is undoubtedly holding back the development of the intellectual and political levels.

In fact, violence as a symbol of our growing irrationality has had an increasing role in activity for its own sake, when no possible justification could be made that the activity was seeking to resolve a problem.

A fully integrated culture would be like the dinosaurs, which had to perish because they were no longer able to adapt themselves to changes in the external environment.

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.

I came into history from a primary concern with mathematics and science. This has been a tremendous help to me as a person and as a historian, although it must be admitted it has served to make my historical interpretations less conventional than may be acceptable of many of my colleagues in the field.

When profits are pursued by geographic interchange of goods, so that commerce for profit becomes the central mechanism of the system, we usually call it "commercial capitalism." In such a system goods are conveyed from ares where they are more common (and therefore cheaper) to areas where they are less common (and therefore less cheap). This process leads to regional specialization and to division of labor, both in agricultural production and in handicrafts.

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.