For a historical figure, Judge Sandra O'Connor is an unpretentious sort.

She has bright hazel eyes, brown-gray hair, a metallic western voice. While the members of the Senate Judiciary Committee ransacked their minds for adjectives sufficient to the occasion of nominally at least passing judgment on the first woman to be nominated to the Supreme Court, she sat with her ankles neatly crossed, gravely heeding each speaker with composed attention.

She is an achieving woman without an edge. She is good-looking without being alienatingly beautiful and bright without being alarmingly intellectual.

Like the man who chose her, Ronald Reagan, she knows the high art of not giving unnecessary offense. Whenever she could, she discoursed on the importance of the separation of powers and the relationship of the states to the federal government, two safe subjects about which she plainly hoped the committee would feel she has the deepest convictions.

She must have convinced even the most dubious conservatives that she is conservative by nature if not in judicial philosophy, of which she disclosed nothing during what one senator ceremoniously called her "ordeal."

The flavor of the proceedings is better conveyed by the fact that two senators during the flowery morning suggested to her that in view of her record and the breathtaking breadth of her support--it goes from Goldwater to Kennedy, from pussycats to militant feminists--that the White House is not beyond her grasp.

Almost two hours of the opening session were devoted to expressions of support. Only one shot was fired over the bow.

Sen. Jeremiah Denton, having first called her "a lady" in forbidden feminist parlance, praised the president for naming her, announced that he liked her, and invited her to say that she might have changed her views about abortion.

"You could still be changing your mind on this issue," he said.

And the question that formed in the hearing room and hung over it while the judge politely fenced and parried was whether she has or she hasn't.

When she finished her brief opening statement, she deferentially sought Chairman Strom Thurmond's permission to give her real answer to the fuming Moral Majority. She introduced her "close" family with as much flourish as so disciplined a character would grant herself: her "dear" husband, John, and their three grown sons, one of whom she hopes, she said ruefully, will give up sky diving. The O'Connors will celebrate their 29th wedding anniversary in December. The nominee spoke of families "as the hope of the world" and, in the only view she volunteered at her debut, of their importance to our nation and our life.

But hers, in the minds of the pro-life groups, is a single-issue nomination. Her four votes as an Arizona legislator on aspects of abortion brought a small demonstration to the sidewalk outside the Dirksen Office Building. The pickets carried signs saying "O'Connor, a poor choice" and wore "No O'Connor" buttons. Mostly middle-aged or older women, they were a remnant of the phantom legions who screamed at her selection and have fallen almost silent--faded under the fulminations of such right-wing stalwarts as Barry Goldwater.

They know as well as Jerry Falwell that there is no stopping the judge. If anything happened to O'Connor on her way to the Supreme Court, the women of America would storm the Senate Judiciary Committee and trash it. So the marchers' mood was relatively mild. One plump nun, cheerily chanting "life, yes, O'Connor no" seemed happy just to be out in the bright September sun. Behind her an elderly gentleman was playing "America the Beautiful" on a trumpet. He appeared to be enjoying the opportunity to display his talent, which may not be entirely in demand, since he was slightly off key. O'Connor knew, of course, that when the last superlative had been decanted, she would have to face the music. When Chairman Thurmond mentioned "abortion," she nodded briefly and glanced over at Denton. "Very well," she said resignedly and launched into a description of the circumstances under which, in 1970, she had voted to repeal Arizona's anti-abortion statute.

It was a long time ago, she said, and besides, the measure died in caucus. She is personally opposed to abortion, "as a means of birth control or otherwise." The law at the time was so severe that a person aiding in the abortion of a rape victim was subject to criminal penalties.

But since then, she said, her own knowledge and awareness on the question has increased. "Thereafter," she said cryptically, "I would not have voted for simple repeal."

During the lunch break, Sen. Arlen Specter, who was set upon by a band of pro-lifers in the corridor, attempted to interpret her sibylline utterance. But since he mistakenly thought she was talking about another controversial vote--a negative for an anti-abortion constitutional amendment in 1974--his intervention was not particularly useful.

After lunch, Sen. Edward M. Kennedy tried, with no better results. Again, Her Honor referred vaguely to the increase in her knowledge and awareness over the past 10 years. When Kennedy asked her if the important thing was a change of views or broadened information, she said cryptically, "the latter."

The fact is that the public has already rendered a verdict on Sandra O'Connor. They agree with the politicians, who believe that Ronald Reagan had his finest hour when he chose her. No single issue can block her way to history and the high court.