The first time she walked into my office in Princeton University's Dickinson Hall, Sonia Sotomayor was holding a paper she'd written for my Contemporary Latin America course. It was marked up with my red ink. Spanish was her first language, and many of her errors reflected its syntax. Where she had written "dictatorship of authority," I had scribbled "authoritarian dictatorship."

That sort of mistake is common when students use different languages at home and at school. Less common was Sonia's determination to overcome this handicap. We spoke at length about her problem. By the time she left my office, Sonia had recognized the mistakes and, more important, why she had made them. For her, she told me recently, it was a "light bulb" moment.

Had I known in the spring of 1973 that this hesitant freshman from the Bronx would be nominated to the Supreme Court 36 years later, I would have taken detailed notes on our conversations and filed them away in anticipation. Unfortunately, all I have are my memories. But Sonia made a strong impression. She was not the best student I taught in my seven years at Princeton — though she certainly was high on the list — but she was the one who took greatest advantage of the opportunities there and emerged most transformed by her experience.

Sonia became a frequent visitor to my office, our conversations ranging from the finer points of grammar to the lack of Latino studies at Princeton and the status of Puerto Rico. She ended up taking five courses with me, including her senior thesis. I became her mentor, and I watched her grow into what one might well call a "wise Latina woman." At Princeton, a tentative teenager — so intimidated that she never spoke in class during her first semester — became a poised young woman who negotiated successfully with top university administrators on contentious issues such as minority hiring practices. It was also there that Sonia Sotomayor more fully explored her ethnic identity.

After conquering Princeton, she is unlikely to be fazed by another institution legendary for its white alpha males — the Supreme Court.

My first impressions of Sonia were mixed. She did not radiate charm or magnetism, nor was she polished or cool. But she had an appealing sincerity and directness, and there was something centered about her that was unusual among first-year minority students at Princeton. There were few Hispanic women on campus in 1973 — the school had begun admitting women only a few years earlier, and Latinos of any gender were rare — so she was doubly an outsider.

Sonia's intellect allowed her to excel at the Bronx's Cardinal Spellman High School and gain admission to Princeton, but there was a big gap between her skills — particularly in writing — and those of the best students at the university, who had attended elite high schools. She was determined to close the gap. That became our project.

With most students, the time I spent marking up papers was largely wasted. But Sonia took the comments seriously. She sought me out to go over her essays. In each paper, I would focus on a different shortcoming: Spanglish, tenses, passive voice. Such constant criticism could not have been easy, but Sonia kept coming back. She even read grammar books during her summer breaks.

Gradually, her essays improved, and by the time she wrote her senior thesis, Sonia had no need to apologize for her writing. Years later, she told me that she was particularly proud of how the second reader of her thesis — a professor who had not worked closely with her — had told her that it was the best-written senior thesis that he had read.

Hispanic students at Princeton in the 1970s had it even harder than black students. The university was confronting its troubled history with African-Americans but had no real Latino history.

Individual Latino students had attended the university before 1972, but Sonia Sotomayor's incoming class contained the first self-consciously Latino cohort at Princeton. They were few in number, young and homesick, without the sounds or tastes of home. All students complain about cafeteria food, but the Latino students' complaints were about identity, not quality — about how alien Princeton felt to them. Sonia told me she had never been so aware of being different.

In the spring of 1974, she and other students came to me and asked me to help create a seminar on the history and politics of Puerto Rico and mainland Puerto Ricans. I was not the ideal person to teach it: I was neither Latino, nor an expert on Puerto Rico. But Sonia knew I believed that college students should have a role in shaping their education, and I was moved by her blend of reason and emotion.

Sonia envisioned the seminar as a step toward a Latino studies curriculum at Princeton, taught by Latino faculty. But I also sensed her desire to explore her identity, a need brought out by the shock of Princeton's WASP culture. So I agreed.

It was a small class of 15 students, mainly Puerto Ricans, but including other Latinos and Anglos. Sonia was always inclusive, even when exploring her heritage. (Her boyfriend and future husband was Irish, not Puerto Rican.)

The class taught critical thinking and featured a collaborative research project on the Puerto Rican community in nearby Trenton. It included mapping the community, analyzing its demographics and developing oral histories of selected families, teaching them how to study communities like their own. Sonia gave back, volunteering as a translator at the Trenton Psychiatric Hospital, where she worked with patients whose misdiagnoses often reflected their inability to explain themselves in English.

The final paper required students to do an oral history of their own families, including their migration experiences. The assignment taught Sonia "a lot about oral history," she recalled recently. But she also thanked me for a more personal reason: Several relatives she interviewed have since died, so her paper became the only history of her extended family.

The seminar also helped Sonia wrestle with what it meant to be a "Newyorkrican" from the Bronx rather than a Puerto Rican from the island. She may have been too intimidated by WASP Princeton to speak in class her first semester, but as a junior in the protected space of the seminar, she was assertive and articulate. What most engaged her were the debates about the political status of Puerto Rico. Despite the class's small size, the principal positions on that controversial issue — from statehood to autonomous commonwealth to independence — all had their advocates. For Sonia, these discussions would culminate in her senior thesis.

By her senior year, Sonia was ready to write about the most important Puerto Rican leader and issue of the 20th century: Luis Munoz Marin and the status of Puerto Rico. Her thesis was extremely ambitious and one of the longest I have supervised, but it was the best paper she had ever written.

Since her nomination to the Supreme Court, however, a couple of marginal phrases in her 178-page paper have been taken out of context by critics, particularly her mention in the preface of her "bias toward independence for Puerto Rico." What she actually said was that her thesis would not reflect that bias, and that unlike most studies of Munoz Marin, her examination of the commonwealth he founded would not be colored by her own preferences.

Moreover, I must take responsibility for her mention of a "bias." I taught Sonia that people often have strong opinions on issues that they care enough about to research, but what is critical is that they recognize those biases and set them aside. That is what Sonia did in her senior thesis. I still think it is a best practice for a student — or a judge.

Her argument — carefully reasoned and supported by evidence from diverse sources — is the kind of judicious analysis that might have led a clairvoyant reader to predict a successful career on the bench.

Sonia's thesis capped a stellar Princeton career. During her last two years, she received A's in almost all her courses, graduating Phi Beta Kappa and summa cum laude. In her comprehensive history exams, she received an A+ from the most difficult grader in the department.

The Pyne Prize — the highest Princeton award for a graduating senior — recognized Sonia's total achievement as an undergraduate, honoring her academic excellence and her leadership. If anything, the prize understated the achievements that I witnessed. At Princeton, Sonia traveled enormous distances, making quantum jumps in skills, sophistication and self-knowledge.

Much has been made of Sonia's comment about the positive effect on her judicial decisions of being a "wise Latina woman" — a quote that no doubt will come up during her confirmation hearings. Personally, I view the comment as a reference to the enriching impact of her life experiences on her work as a judge.

Princeton played a key role in those experiences. It was there that she grew in confidence. It was there that she learned to read and write critically — and her skills became equal to the best of her generation. It was there that she developed a clearer sense of what it meant to be Latina and Nuyorican.

At Princeton, moreover, Sonia learned to build coalitions, to persuade others to live up to their values and to use the law as an instrument of social change.

By graduation, Sonia could compete with anyone and succeed anywhere — including on the Supreme Court.