TWO WORLDS intersect in the case of the civilian Navy counterintelligence analyst arrested on espionage charges while bolting into the Israeli Embassy.

One is the secret world of espionage. There, it is no surprise to find that some Israelis have been spying on the United States. No doubt people consumed by the sense of living on a narrow security margin find it difficult to forgo an activity that they think might widen that margin. For the purpose of espionage is not simply to keep an eye on one's enemies. It is to keep from being surprised, and one's friends can cause surprises no less disruptive -- sometimes more so -- than one's enemies. As generous as the United States is to Israel, there cannot fail to be things the Israelis feel they could learn that would reduce still further the chance of someday being surprised.

It was precisely to reduce the chance of surprise, you will recall, that the United States dispatched the USS Liberty to spy electronically on Israel and the Arab combatants in the 1967 Middle East war. The Israelis shot up the ship in an incident the bad memory of which lingers still. But a prudent person has to hope that Washington did not then decide there was no further reason to keep an eye on Israel.

Meanwhile, however, there is also the open world of politics in which some limitations must be imposed on the ways the two sides seek information about each other. This is the world evoked by President Reagan's reported question, "Why are they doing it?" Indeed, how could the Israelis spy, in an intrusive risky fashion, on the country that is their leading strategic and financial support and already their partner in extensive intelligence collaboration? The Israelis are holding their own discussions about who is to blame, and it is important to remember that it is not yet known just who authorized this operation or at what level it was conducted. Still, it is enough for Americans to find that some representative of a friendly state saw fit to conduct the kind of operation against its patron that is usually associated with the intrigues of a hostile power.

The value of whatever may have been taken from the files cannot possibly come near outweighing the value of what may yet be taken from the relationship. The notion that an ostensibly friendly intelligence service could not keep its distance from an American civil servant does violence to the mutual trust that Israeli officials regularly describe as the sine qua non of American-Israeli relations.

No doubt many people will now feel that the first priority is to contain any damage done to American-Israeli ties. Others will feel a sense of deep and pained puzzlement. The American courts will handle the case of the Navy suspect. The more interesting question is what the Israelis will tell us about what was going on.