Few things are as monumentally ugly as the Israeli separation wall on Jerusalem's edge. For miles and miles, it runs along stony hills and across valleys terraced with olive trees, cutting through towns and fields, cleaving families from their homes, farmers from their land. Its concrete slabs are more than 20 ft. high and crowned with coils of razor wire; the wind seems to blow every stray plastic bag in the Holy Land into its cold shadows. The Palestinians like to say, accurately or not, that the wall can be seen from outer space.
In 2002, Israel started building the barrier--part...