If you wanted to explain why some countries seem more favorable toward European integration than others, what cleavage would be most important: North-South, East-West, rich-poor, or Catholic-Protestant? No doubt any difference matters, at least potentially, and many of these cleavages are overlapping. We could invent a few others as well related to linguistic families, kinship structures, or even physical geography. Nevertheless, it helps to tell the story if you can focus attention on whatever offers the best prospect of combining simplicity with coherence. By implication, you have to make a choice about what matters most.
Erik Jones 