A tragic condition underlies all the backing and filling in the Middle East. Both Egypt and Israel are dependent on help from the outside for their very existence. When peace and cooperation could mean so much, it makes the debating points over principles seem trivial if not irrelevant.

The plight of Egypt has been well advertised. It is evident to even the most casual visitor to Cairo. Existing along with a very thin slice of wealth, poverty spills over into fetid streets and even into the City of the Dead, the cemetery in Cairo that has been taken over by the dispossessed.

Aid from Saudi Arabia, estimated at $1 billion a year but probably considerably more than that, together with a much smaller amount from the United States, keeps that shaky structure afloat. One of the ironies in the first rejoicing in Egypt over President Anwar Sadat's dramatic journey to Jersualem was the conviction among the crowds in the streets that it would surely mean an end to the plague of poverty.

Less well advertised is the plight of Israel. A country of somewhat more than 3 million Arabs, and the demographic figures show all too plainly that they are being outbred at an ever-increasing rate by the Arab mass. And that gets down to the hard fact of population growth or the lack of it on which Israel's progress depends.

The upward movement of the economy, according to an official estimate, depends on an added 50,000 to 60,000 new citizens each year. What with the exodus of many of the young, the total has been far less than that.

In 1977 there was some improvement. The official figure for the outflow was 16,000, against an inflow of 24,000 making a net gain of 8,000. Virtually all the newcomers were from the Soviet Union. This has been helped by the fact that while until recently 55 percent of those departing the Soviet Union opted to go to the West, mostly to the United States, the ratio has now been reversed to 55 to 45 in favor of Israel.

The military demands of what is in effect a garrison state are responsible for the exodus of many of the young. Compulsory military service of three years for both young men and young women is followed by a reserve requirement with call-ups beyond the age of 40. Military action like the recent incursion into Lebanon and the Yom Kippur war of 1973 means that experienced reservists are back in uniform, their civilian lives disrupted.

On top of that are the severe economic pressures of high prices, a scarcity of housing and government pressure to keep wages low. Inflation in 1977 reached a high of 34.6 percent (though devaluation of the Israeli pound has brought that down to an officially estimated 1.6 percent).

Israel receives from the U.S. government annually $1.8 billion. Sales of military material account for $1 billion of the total, although that becomes in part a grant. The 800 million is a grant of economic aid.

In addition, contributions by individual Jews add up to sizeable amounts and particularly at periods when Israel appears threatened. In 1967, at the time of the Six Day War and again in 1973, those contributions spurred by deeply emotionl appeals, reached $500 million. They are exempt from U.S taxation.

The relationship between American Jews and Israel is complicated by the contrast between American affluence and the dangers and hardships endured by the Israelis. In one interpretation, that induces a sense of guilt assuaged by annual generous giving.

The emigration of American Jews to the Jewish homeland is a delicate question. Frequent appeals are made to the 6 million or more American Jews but only a trickle have responded, according to the official Israeli view. In the peaceful years that number expanded somewhat. In 1976 it was 3,500; in '77, 4,500.

All this is not to say that the dependence of Egypt and Israel on help from beyond their borders would end with a peaceful settlement between the two. But the benefits would be incalculable. Israelis with their great expertise in irrigation and a wide variety of other fields cooperating with Egyptians could help to reverse the tide of poverty and misery.

As for Israel, the fact of a peace in which Jordan might eventually join would surely see a lessening of tensions. It could eventually mean a reduction in the military service of the young. While it would not end the threat of the Palestinian terrorists, it might well mitigate it.

In that light the bleak stalemate in the Egyptian-Israeli peace attempt is a tragedy. No matter how dire the consequences in the months to come, it is for the present the closing of a door on an avenue of hope.