Sunday is the 25th anniversary of Clarence Thomas being sworn in as an associate justice of the Supreme Court of the United States. From his beginnings in Pin Point, Ga., where he lived in a shanty without indoor plumbing during the Jim Crow era, he has become the longest-serving black justice on the nation’s highest court. He emerged dignified from an undignified Senate confirmation and went on to produce a body of jurisprudence that has been praised by constitutional scholars across the ideological spectrum. But because he’s a black man who challenges liberal orthodoxy, his legacy has often been minimized.

His is a story that should be celebrated by all Americans. That it isn’t is a travesty.

As Supreme Court correspondent Jan Crawford wrote nearly a decade ago, “From the beginning, Justice Thomas was an independent voice” who began making his mark as soon as he arrived at the Court, voting initially by himself to dissent in Foucha v. Louisiana, a case concerning the authority of a state to confine a defendant found not guilty by reason of insanity.

He circulated a powerful lone dissenting opinion that argued that “Removing sane insanity acquittees from mental institutions may make eminent sense as a policy matter, but the Due Process Clause does not require the States to conform to the policy preferences of federal judges” and warned that the court comes nearest to illegitimacy when it strays from the language and design of the Constitution in its interpretation of that text — an argument that persuaded Chief Justice William Rehnquist and Justices Anthony Kennedy and Antonin Scalia to change their votes.

Since then, Thomas has repeatedly led the court back to the original meaning of the Constitution with thought-provoking separate writings that explore the historical record.

Recently, he produced a trio of opinions, Department of Transportation v. Association of American Railroads, Perez v. Mortgage Bankers Association and B&B Hardware, Inc. v. Hargis Industries, Inc., analyzing the constitutionality of the modern administrative state in light of founding-era understandings of the separation of powers in our Constitution.

Of Thomas’s approach, SCOTUSBlog’s Tom Goldstein, a well-regarded Supreme Court practitioner, says: “I disagree profoundly with Justice Thomas’s views on many questions,” but if “the measure of a Justice’s greatness is his contribution of new and thoughtful perspectives that enlarge the debate, then Justice Thomas is now our greatest Justice.”

Why, then, is he rarely mentioned along with great jurists like Oliver Wendell Holmes, Felix Frankfurter or Scalia, his recently departed contemporary?

One reason is lingering sentiment about Thomas’s confirmation process, which indeed was, as he described it, an unjust and malicious “high-tech lynching.” Perhaps another is Thomas’s silence on the bench. He prefers to listen, and not ask questions, during lawyers’ presentations, a consistent practice that has drawn rebuke from his critics.

But if the measure of judicial accomplishment is the number and quality of opinions a justice writes — and not the questions he rattles off during oral arguments — then by that measure, Thomas is among the most impressive justices: He has now written more than 500 opinions, many of them contributing new and painstakingly researched analysis. His opinions in United States v. Lopez, McIntyre v. Ohio Elections Commission and McDonald v. City of Chicago are just some examples from the illustrious list. He has also demonstrated the fortitude to hold true to his jurisprudential principles in the face of withering attacks.

Mainly, though, it’s that Thomas, throughout his career, never wavered from a set of principles that many liberals don’t think a black man can legitimately hold. He believes in individual rights, not group rights, a view enshrined in the Declaration of Independence. He opposes racial preferences both because they are bad policy and because they have no basis in the Constitution. Thomas held those views long before he arrived on the court, but they have been powerfully expressed in many of his opinions.

In his recent concurrence in Fisher v. University of Texas at Austin, which involved a challenge to affirmative action in the university’s admissions program, Thomas quoted the arguments made by the lawyers in the landmark Brown v. Board of Education case that, “ ‘No State has any authority under the equal-protection clause of the Fourteenth Amendment to use race as a factor in affording educational opportunities among its citizens’ ” and continued that “The Constitution does not pander to faddish theories about whether race mixing is in the public interest. …  All applicants must be treated equally under the law, and no benefit in the eye of the beholder can justify racial discrimination.”

Thomas reviewed the university’s arguments justifying its affirmative action program, noted the similarities between those arguments and those previously made by defenders of slavery and segregation, and concluded:  “Racial discrimination is never benign.”

As a result of these views, Thomas has earned the scorn and disdain of traditional black civil rights leadership and special interest groups — his opinions are a threat to their calls for quotas and set-asides.

Thomas’s critics have not only dismissed his judicial record, they have attempted to minimize him, personally, at every turn. Over the years, more than one has characterized him as an unqualified “affirmative action” appointment to the court, despite his having graduated from Yale Law School, chaired a federal agency in a manner that earned the praise of The Washington Post and served as a federal circuit judge.

Some of his critics take the criticism a step further, claiming that he was the beneficiary of affirmative action programs — an assertion he rejects — and that, by now opposing such programs, he has essentially turned his back on the black community.

Nothing could be further from the truth.

As University of California at Berkeley law professor Angela Onwuachi-Willig, a self-described “liberal black womanist,” concludes, Thomas’s opinions reflect a profound concern for the black community. And, she writes, he “has been unfairly subject to the stereotype of black incompetence,” citing the example of Democratic Senator Harry Reid’s 2004 statement, in response to a question about whom he could support if there were a chief justice vacancy, that Thomas “has been an embarrassment to the Supreme Court. I think that his opinions are poorly written.”

Contrast that to his description of Scalia — with whom Reid likely disagreed with on most controversial issues — as “one smart guy.” Such examples go a long way toward explaining how Thomas came to resent the stigmatizing impact of racial preferences, and critics who suggest that Thomas is not qualified and only on the court because of his race — in effect, an affirmative action appointee — make his case for him.

To know Clarence Thomas, both as a justice and a friend — to have witnessed his generosity of spirit firsthand — has been a true honor.

When I was diagnosed with cancer shortly after his confirmation, Thomas visited me every day, and though he was still fresh from his public ordeal, he focused only on my challenges.

At least once a year for many years, he and I went to visit his eighth-grade teacher, Sister Mary Virgilius Reidy, and several other nuns at their retirement home in New Jersey. When she passed away in 2013 at age 100, Thomas and I attended her funeral. He has been involved with the Horatio Alger Association, an organization that provides scholarships to children from the most challenging of backgrounds, for years — spending hours with young adults, learning their stories and helping them on their journey to a better life.

I brought Thomas to a meeting at the Justice Department on the day Justice Thurgood Marshall retired, filled with excitement that this good man could be nominated by President George H.W. Bush. I then spent the next several months working around the clock to rebut the attacks on Thomas’s qualifications and character. He was devastated — it’s not hard to imagine how much one’s good name would matter to a person who grew up with little else. This all-out assault and Thomas’s courageous and defiant response are seared into my mind, and indeed my soul.

For those of us who worked on his confirmation and went through that terrible ordeal with him, his stellar record on the court has only confirmed the value of that fight. The sustained effort to discredit Thomas because he dares to present a view that cuts against the grain is both pathetic and a waste of time for anyone who claims to genuinely care about racial progress.

In 1998, one prominent civil rights leader opposed an invitation to speak extended to Thomas by the National Bar Association, the preeminent black lawyers’ association.

But Thomas addressed the NBA that year, and as he stated in his speech: “Isn’t it time to acknowledge that the problem of race has defied simple solutions and that not one of us, not a single one of us can lay claim to the solution?” His critics may not make any such acknowledgement, but I hope that in time, they will acknowledge their error about him.

History will look kindly upon Justice Thomas’s judicial legacy and on him as an individual. The people who know him best certainly do, and in time, I believe, most Americans will, too.