Joseph DiSalvo makes his living dealing in hard facts. The former corporate litigator is now a partner with a successful boutique private equity firm. Lots of balance sheet analysis, risk management and governance goes into his line of work.

That’s why I was surprised to learn one day over a beer (full disclosure: Joe is my brother-in-law) that the person who made the biggest impact on his career wasn’t the guy who taught him finance or contracts, but his undergraduate philosophy professor at NYU, Bob Gurland.

Gurland just might be the most popular professor in NYU history, even if most people outside the university’s downtown Manhattan campus have never heard of him. According to former students and NYU colleagues to whom I spoke, he is also possibly the most important teacher of philosophy in the country.

That’s right: Teacher. Gurland eschewed the research and publication circuit of academic self-promotion that has defined “higher education” in recent generations, and instead poured his heart into expanding the minds of his students using Plato, Socrates and Aristotle as his template.

He retired from NYU in 2019 after more than 65 years in the profession, more than 50 of them spent at the university, where students packed his classrooms semester after semester. More than 25,000 students have heard him lecture and studied his lessons, I am told. They’re now leaders in academia, business, medicine and law, and many credit Gurland for their success.

Gurland’s remarkable career and life, which traces its origins to his working-class roots in The Bronx, is the subject of a fast-moving documentary film titled, fittingly, “Bronx Socrates.” It was screened by NYU this past Friday as part of a celebration I attended of Gurland’s legacy at the school.

If you can appreciate someone with a passion for teaching (Gurland actually began his career as an elementary-school teacher before earning master’s degrees in education, mathematics, and his Ph.D. in philosophy); and baseball (he was a minor league baseball player for a stretch); and on top of it all, jazz (he played the trumpet professionally with the likes of Gene Krupa, Lionel Hampton and Count Basie), you will enjoy this feature.

To be sure, this is not unbiased journalism. It is a well-told and absorbing homage from Gurland’s former students, who believe their success began in his classroom.

“Gurland is so inspirational to so many as a teacher because he never used his time with his students to tell them what to think, but instead was deeply committed to teaching them how to think,” DiSalvo, the film’s producer and director, told me.

Gurland, as the film shows, was also a thespian as much as a professor. You could be one of 100 students packed into an auditorium and you felt he was speaking directly to you about the meaning of life or the crisis of values.

“I didn’t want to waste my students’ time,” he says in the film. “I wanted to cover things that I felt were important and would have a real, positive impact on how they thought and how they lived.”

The film will also help you reflect on the current disease afflicting higher education that many more Bob Gurlands would undoubtedly help cure. In short, college has become a lousy investment for far too many grads.

By some estimates, the cost of an undergraduate degree has increased nearly 170% since 1980 — even if the rise has leveled off a bit in recent years. The average student at a four-year college is saddled with tens of thousands of dollars in debt after graduation — and more for those who attend higher-priced private universities.

And just 30% of college budgets are directed at actual instruction, even if you’re getting a four-year degree from a prestigious private university.

College grads often can’t afford to move out of Mom’s basement because they didn’t come out with the necessary skills to ­compete.

Yes, Gurland specialized in teaching one of academia’s softer skills — philosophy — but he did it in such an intellectually challenging way that it prepared his students for the rigors of the business world at least as much as any finance course.

Moreover, there were no safe spaces in his classroom.

I don’t want to give too much of it away, but the film was maybe most compelling describing Gurland’s time teaching both students and military faculty at West Point in the mid-1970s. The Army was in soul-searching mode after the disastrous conflict in Vietnam. West Point also was reeling from a cadet cheating scandal in 1976 and chose Gurland to create an ethics program.

Gurland took a sabbatical from NYU, and not long after he started he told his supervisors something they probably didn’t want to hear: “They were preparing guys to take on the responsibility of leadership they were not prepared to discharge.”

The military, he says, had a “suspicion of intellect . . . thinking is not such a good idea.”

Gurland set out to change that mindset because, among other things, he believed philosophy and the rigors of teaching it could prevent the next Vietnam War. Such rigors also produced a generation of intellectually solid business leaders, which is why we need more Bob Gurlands.