A bomb exploded at a Paris synagogue on Friday, killing four people. It was a crime not only against Jews but against an idea of civilization that was, in Europe, largely invented by the French. In response, on Tuesday, a vast public procession marched in protest through Paris to the Place de la Republique. An extraordinary range of political parties, civic organizations and labor unions took part. It was noted that the government did not.

In the week before the synagogue bombing, four Jewish community buildings in Paris had been machine-gunned. This week there have been attacks on businesses and homes of Jews in several cities and towns in southern France. There is no reason to suspect any broad shift toward anti-Semitism in France. These events will absolutely turn out to have been the work, as usual, of a small number of people alienated from any recognized political movement. But something has happened, apparently, to set off this sudden series of attacks.

Perhaps there is a certain relationship to the terrorism carried on in Paris by some of the Middle Eastern and North African governments. Their targets have usually been exiled politicians and public figures. Some of these assassinations have apparently been organized with the help of these countries' embassies in Paris. The French government's attitude has been ambivalent. It doesn't like the gun-play on French territory. But France has worked for years to establish itself as the special friend of the Arabs -- a position that, if it were ever achieved, might be expected to produce benefits like access to oil and to the markets of newly wealthy nations. The French have been reluctant to enforce the normal rules tightly on the Arab and Iranian missions. These missions are, to one degree or another, hostile to Israel. As they would immediately point out, there is a vast difference between hostility to Israel and the incitement of local anti-Semites. But in the peculiar psychology of terrorism, there seems to be a certain resonance here. The connection is neither direct nor rational.But it is not rational people who set bombs at synagogue doors.

The day after the procession, the French government sharply changed its tone. The president and the prime minister both personally delivered denunciations that were unequivocal. "Terrorism is a faceless crime that, by its nature, strikes only innocents," Prime Minister Raymond Barre declared. "The horror here is further aggravated by the fact that the attack was aimed at those among us who, hardly 40 years ago, underwent unspeakable experiences." The Interior Ministry is pursuing the bombers with the special vigor, not to say ferocity, of which the French police are capable. But for the future, the French are going to have to come to terms with the reality that domestic terrorism is not separable from international terrorism. To suppress one, they are going to have to deal with both.