Of course, it is very hard to reconcile a tolerant and secular rule of law with serious and passionate religious belief, as our own history shows. Nevertheless, we should never doubt the achievement of Western civilisation in developing systems of law founded in a far-reaching ‘agreement to differ’, and authorised not by divine command but by human judgment. From this achievement others have flowed: secular institutions, democratic government, free universities, science, prosperity and commerce. It is the real cause of the singular most revealing fact about the present ‘clash of civilisations’, namely that Muslims are migrating in their millions to the West, while nobody is migrating in the opposite direction.

Or, as one blogger put it recently (I forget who): "Follow the traffic."

Update: It was Mark Steyn, not a blogger.