YOU WILL pardon us if we show that, like everyone else, we are coming to terms only by stages with the mind-boggling fact that President Anwar Sadat may visit Jerusalem as soon as next week and Prime Minister Menahem Begin will likely visit Cairo in return. We reflected yesterday on the potential of this initiative to transform the character of the conflict that he has kept Arabs and Israelis at swords' points for years. Today we would observe how it may also transform the diplomatic process the administration has set in train.

President Carter has striven for a general settlement on the sensible theory that it was at least worth trying as a logical follow-up to the step-by-step diplomacy of the previous administration had the identical strategy. But undeniably this has compelled Washington to accommodate not just Egypt, whose greater readiness for settlement is nowhere doubted, but also Syria, which - being more Palestinian-minded - has proven a tougher nut to crack. It was precisely to bring Syria and the Palestinians to Geneva, symbol of the comprehensive approach, that the United States justified its recent outreach to Moscow.

Now, however, a way to resume the easier step-by-step approach is in sight. Egypt has stepped outside the American-directed Geneva process and made its own bid to Israel. Obviously, Mr. Sadat will present all the Arabs aims. No less obviously, he will emphasize Egypt's particular aims. Being primarily territorial, these are substantially easier for Israel to meet. So prospects of a separate Israeli-Egyptian peace, presented no doubt as a way station to a larger settlement, are greatly enhanced.

American officials indicate they wish to fit the Sadat initiative into their previous Geneva plans: The State Department anticipates Arab-Israeli "proximity talks" next month. This suggests, however, not just that officials are as nonplushed as the rest of us but also that there may be a certain bureaucratic tendency to cling doggedly to established positions even after they have been overtaken by events.

Just a few days ago Mr. Carter held out only a hope that the parties would send delegates to Geneva. Now two governments have decided to meet at the highest political level in one and then perhaps the other capital. This seems to us to have overtaken the earlier and worthy American purpose, which was to act in the absence of spontaneous activity by the parties. Artificial diplomatic respiration loses much of its function, however, when the patients, or two of them, begin to breathe by themselves.The United States should supply what support Egypt and Israel ask for their dialogue, remain ready to stretch (at Geneva) a safety net, and meanwhile sit back and let this fantastic new development unfold.