The comedian Louis C.K. has this insightful bit about time machines. They’d be great for white men, because pretty much any number we hit on the dial — 1855 or 1950 — works OK for us.

But for African-Americans and women. Slide that time-travel lever too far back, and you may find yourself landless with no voting rights, or worse, in chains.

Me, though, who can hate a white kid from Carroll, Iowa? Now or then. Whenever the then.

Back in the late 1980s, as I left western Iowa for the north side of Chicago and Northwestern University, I’d never experienced demographic or racial hate directed at me.

Many weekday evenings in my underclassman days at Northwestern I’d join my friend Hayden to walk from the residence halls on the south side of the university to our north-campus fraternities for dinner. I was a Sigma Alpha Epsilon (like former Gov. Robert Ray was at Drake University by the way) and Hayden would go on to the Northwestern chapter presidency of the historically Jewish fraternity, Zeta Beta Tau.

One night, as we walked back, Hayden and I noticed lines of African-Americans, colorfully attired in clothing inspired by their ancestral continent, filing into the Alice Millar Chapel.

Hayden and I were nothing if not shy. So we asked what was going on inside.

Louis Farrakhan, the Nation of Islam leader, was speaking. We joined the crowd, found seats as two of the few white people gathered to hear Farrakhan. The Nation of Islam’s over-arching philosophy could be described as black separatist. Its history is so littered with prejudice, though, that the Southern Poverty Law Center (the same organization that tracks the KKK) designates it as a hate group.

“[T]he Jews don’t like Farrakhan, so they call me Hitler,” Farrakhan said in a radio interview, March 11, 1984. “Well, that’s a good name. Hitler was a very great man. He wasn’t a great man for me as a black person, but he was a great German. Now, I’m not proud of Hitler’s evils against Jewish people, but that’s a matter of record. He raised Germany up from nothing. Well, in a sense you could say there’s a similarity in that we are raising our people up from nothing.”

I can’t recall exactly what Farrakhan said the day I heard him at Northwestern. It’s one of the few speeches I’ve attended without a reporter’s notebook. But I vividly remember the well-armed Nation of Islam’s bow-tied guards standing next to nearly every other pew with military-style firearms. There were some exchanges between Farrakhan and Jewish people in the audience.

The American Jewish Congress says Farrakhan is “one of the country’s most prominent and unrepentant public bigots.”

I absorbed the palpable pronounced hatred in that place of worship. I saw the ugly history that my friend has to face, in some way, every day, as a member of the Jewish faith.

As a white man, a Protestant, I found myself in the rarest of destinations one wouldn’t select in Louis C.K.’s imagined time machine.

These memories surfaced with great clarity two weeks ago as I listened to Iowa State University students at a diversity forum held in the wake of a Cy-Hawk game-day incident outside Jack Trice Stadium. In the mid-afternoon before the game, angry tailgaters tore down signs, hurled slurs and threw spent beer cans at the roughly 30 to 40 college students, activists and their supporters, many of them Latino, gathered to protest Donald Trump, not just on immigration, but on women’s and veterans’ issues.

We covered the justifiable anger from advocates associated with the League of United Latin American Citizens and Students Against Bigotry at the ISU forum.

But near the end, in the open-microphone session, something disturbing happened.

A gay student rose and said he didn’t want to hear evangelical Christians who think he’s going to hell speak on campus. Or, if they do, the university should place warning signs around the speech location, said this student in a plea for what amounts to a political-correctness perimeter.

A conservative kid, who waited some time for his chance at the microphone, said many students of like philosophical mind are furious with the way Joni Ernst and other leaders with right-leaning views are treated on campus. A Latino panel member called this conservative student “ignorant,” and the 600-member audience essentially shamed him away from the microphone. For what?

Terms like “micro-aggressions” and “triggers” filled the Great Hall that night in Ames from kids calling for the authorities to keep them carefully cocooned from any thought or word that might upset them, ding the self-esteems their helicopter parents have erected over two decades with participation trophies. No wonder Chris Rock and Jerry Seinfeld and Larry The Cable Guy don’t want to play college campuses anymore.

“Students right now are very sensitive to speech and expression they don’t like,” Iowa State University President Steven Leath told this newspaper in an interview. “And we have to guard against that because an educational institution, part of the experience is what you learn outside of the classroom. How do you deal with life? How do you deal with other people? But we also have to draw the line at stuff that becomes hateful.”

Actually, a university shouldn’t draw that line.

We need to hear the hate speech so we understand its motivations, see its effects on the faces of those around us, so we can combat it. We can’t just pray the hate away. How can we fight what we don’t know? Hate breeds better in the backwater darkness, where bombs are wired and deadly fantasies reinforced, than on the front steps in the light of day.

A little more than five years after I saw Farrakhan at Northwestern he emerged with his Million Man March on Washington in 1995. At the time, I was a congressional staffer working in the Longworth House Office Building, near the Capitol, where Farrakhan would espouse wide-ranging views for two hours. Now 82, Farrakhan commemorated the 20th anniversary of that march just this past weekend.

The Capitol offices resembled a ghost town that day in 1995. People fearing traffic snarls (the polite excuse) and, well, a million black men in town (the ugly truth), didn’t show up for work in what was widely accepted as a day off.

But I was there that day on Capitol Hill. Outside of my office. Listening. One minute, I’d be offended. The next, confused with what the Washington Post calls Farrakhan’s numerology and creation myths.

Mostly, I viewed Farrakhan just as I do today — as absolutely insane, a demagogue in the great American tradition of such men.

What remains true, regardless of what I think, is that Farrakhan, who received national media coverage Saturday, has a following. So do the gay-hating speakers telling ISU’s homosexual kids they are destined for damnation. So do countless other espousers of prejudice and hate — all of whom should be welcome to speak at our state’s universities to explain their controversial views on race and rape, immigration and religion, food and farming.

Students should run to the hate, challenge it in their own words, rather than appeal to the masters of the Ivory Towers to keep distressing ideas from their too-sensitive ears, their too-rattled senses of self.