Starting with his extraordinary televised three-day visit to Israel, Anwar Sadat has transformed more than the political landscape of the Middle East. He has surely also transformed, or at least substantially altered, the American perception of the Arab and his cause. Unlike the set pieces to which we have become accustomed - the oil-rich sheik, the terrorist, the ululating crowd - Sadat was neither alarming nor strange. He was politically plausible and humanly familiar.

That any of this should have come as a revelation to anyone is a comment on two things. One is our own cultural insularity. The other is the general willingness of Arab leaders to let their purposes be defined by the aberrant and extreme. Sadat did not destroy these two pillars of our misunderstanding. But he made a powerful and valuable assault on them, one that needs to be continued.

A few years ago I got a call from a Palestinian-born Arab who was the head of a national Arab-American lobbying organization. He wanted to pursue some things I had aid in a column about Gen. George Brown and American Jews, and suggested that we meet for lunch - which we did. It was a pleasant and instructive encounter, but what I remember best about it was not our discussion of Middle East realities. Rather, it was his very first remark to me after we had both been seated in the overpriced, posh restaurant. Did I mind if he asked a personal question? Well . . . no, go right ahead. It was this: "Tell me frankly now, what did you think I would look like?"

I assured my new friend that in fact I had not envisioned what he suspected: a scruffy fellow in unkempt national dress, with a couple of sheep tethered to his chair. Still, he had a point. Some vague thrill of danger or at least of the exotic had walked with me from my office to our lunching place, only to be dissipated by his business-suited presence. And I think it tells you something about the power of the Arab caricature in our culture that this could still be true in Washington in the 1970s - a city of diplomats, journalists and Foreign Service officers who are eager to share their firsthand experience of the Middle East.

That caricature, incidentally, is one of the very few "ethnic jokes" still indulged by our cartoonists and stand-up comics. It is somehow considered permissible where comparable jokes are not, and I do not think this is wholly owing to the absence of a big enough Arab-American political constituency to raise hell. There is a dehumanizing, circular process at work here. The caricature dehumanizes. But it is inspired and made acceptable by an earlier dehumanizing influence, namely an absence of feeling for who the Arabs are and where they have been.

At about the 99th parting-of-the-Red Sea image invoked for the Sadat visti, it occured to me that our scribes and pundits had nothing but Old Testament lore at hand in the way of historical context for the visit. Between the Bible and the Balfour Declaration, the Arabs are off our radar screen. That is an exaggeration, but not by much. I should probably point out around here that the term "Arab" is widely misused to cover, among other things, all of Islam and all of those (Persians, Greeks, Egyptians, Turks and so on) who ever inhabited the area we now think of as the Middle East. But since we are historically no better informed on any of these than we are on specifically Arab affairs, the distinctions hardly matter. The whole area and its people are off our screen insofar as the past couple of millennia are concerned.

This fact contributes greatly to our sense of cultural estrangement and also to our arrogance - neither of which is justified in historical terms. At a time when Western civilization was pretty much going under, Arab scholars were translating, studying and keeping alive much of the classical Greek philosophy and science on which the West was built. But we have more or less excised from our collective consciousness the Middle Eastern connection: the centuries-long supremacy of that part of the world as a center of intellect, commerce and power; the fact that we are, all of us, legatees of Arab and/or Muslim and/or Middle Eastern culture in some respects.

But there is more than an awareness of the historical human reality of the Arabs to be gained by looking in on the past 1,500 years or so of their existence. To do so is to dispel the ignorant notion, so wide-spread in this country, that the Jews and the Arabs are settling some ancient score, that their modern-day struggle is merely a 20th-century incarnation of an intractable religious dispute with roots going deep into history.

That some pretty grisly episodes between the two took place over the years is not to be denied. Nor, however, is it to be denied that there were prolonged periods after the rise of Islam of extremely good relations or that, all things considered, the Jews tended to prefer the ascendancy of the various Muslim caliphates to that of the Byzantines and crusading latins. The Al Aksa Mosque where Sadat went to pray in the Old City of Jerusalem is in the area of the most terrible crusader slaughters of Muslims and Jews. There was much in the two peoples' past to bring them together.

And there was this historical circumstance: At more or less the same time that the Jews "disappeared" into Europe, the Arabs were overwhelmed by other powers or absorbed into the societies they had dominated so that for (roughly) 500 years - until the beginning of this century - each people was offstage, mingled one way or another in other national cultures.Their nationalistic impulses flowered at the same time, concentrated in the same region, had similar intensities as a consequence of their suffering - different kinds of suffering, but suffering nevertheless. That is the context in which the 20th-century conflict between Arab and Jew is occurring and the only one in which it can be understood - or resolved. It is also the context in which Sadat proffered his message of reconciliation.

He spoke as a man of the 20th century. He bore his national and religious heritage with pride and confidence, but without swagger or put-them-to-the-sword rhetoric and posturing. Will he be able to elicit, over the long term, a sufficient response from the Jews? Will he be able to superimpose his own image and restraint on the murderous, reckless rage of some of his fellow Arabs? Those are questions that can't be answered yet. But I think it is safe to say that when the plane touched down in Jerusalem, Sadat stepped into American political reality, just as surely as he stepped onto Israeli soil. If he has helped us to see the side he speaks for in the Middle East with more compassion, and in a less sinister, preposterous, Ali Baba way, then I would say the same thing I felt upon learning that Sadat was prepared to acknowledge the legitimacy of the Israeli state: about time.