In September, 1963, two African-American teenagers enrolled in the 12th grade at Murphy High School in Mobile, Ala. Governor George C. Wallace would not let them in. On September 6, Wallace sent 150 state troopers to the city, “without,” The New York Times reported, “announcing their purpose.” President John F. Kennedy had to appeal to Wallace directly to cease interference—and threaten his own, if the governor would not respect federal law and desegregate the schools. On September 10,  the two young students made their way up the steps to class, holding schoolbooks, passing cameramen.

Tim Cook was born in Mobile in 1960. This standoff brewed not far from his childhood home. The same year, a few short hours away, Dr. Martin Luther King, Jr. wrote his “Letter from Birmingham Jail.” As a kid, Cook saw, from his bicycle, Ku Klux Klansmen setting crosses on fire where black neighbors lived. He recognized a local church deacon among the hooded men. When he was not yet 8 years old, King was assassinated in Memphis, Tenn.

Cook is now 53, and the CEO of Apple Inc., which has the highest market value of any publicly traded company in the world. On Thursday morning, he published an essay in Bloomberg Businessweek, which twice made mention of King. Cook wrote that he keeps a framed photo of the civil rights leader in his office at Apple.  And he wrote, “I believe deeply in the words of Dr. Martin Luther King, who said: “Life’s most persistent and urgent question is, ‘What are you doing for others?’ ” I often challenge myself with that question.” That question, he wrote, is "what has led me to today," and his public announcement that he is gay. Cook wrote crisply and to the point: “Let me be clear: I’m proud to be gay, and I consider being gay among the greatest gifts God has given me.”

Cook has never spoken publicly about his sexual orientation. He acknowledged, “Apple is already one of the most closely watched companies in the world, and I like keeping the focus on our products and the incredible things our customers achieve with them.” But a sort of moral fiber, a thrusting of dignity, has come up before in his public conversations. It's apparent in his Businessweek essay: Being gay, he wrote, has given him "the skin of a rhinoceros" and has made him more empathetic. The chairman of Apple’s board expressed “wholehearted support and admiration” for Cook, and in a statement said that “his decision to speak out will help advance the cause of equality and inclusion far beyond the business world.”        

On exactly this theme of equality and inclusion, I spoke Thursday by phone with Senator Tammy Baldwin of Wisconsin.  A Democrat,  Baldwin is the first openly gay U.S. senator. She told me, “I read Tim Cook’s piece and was really moved by what he had to say—that, despite his desire for privacy, he realized what an impact he could make by being out, by publicly acknowledging that he’s gay.”

“He holds a very prominent position,” she went on. “When a young person, perhaps growing up in a hostile climate, [who might] question their ability to succeed in life and their careers… For a young person in those circumstances to read what Tim Cook has written can be transformative.”

Baldwin told me of a number of moments in her own life that opened the floodgates to light. “I will never forget watching Geraldine Ferraro accept the nomination as vice president on the Democratic ticket. I thought, boy—as a young woman, I can aspire to anything. The sky’s the limit. I am also aware of the impact that reading about [slain San Francisco Supervisor] Harvey Milk and his political career had on me as, again, a young person who was determined to be out and involved in politics. And I know that Tim Cook’s writings are going to have that impact on an enormous number of young people.”

She said that young people sometimes reach out to her with their own tales of struggle. “On occasion I’ll receive a letter from a young person who has just come out to him- or herself, to family or to people in the community, with a really frank and honest expression of how much it means to that individual to have role models who have succeeded in society. Some of these letters we have received over the years have been incredibly inspiring to me.”

These letters, she said, encourage her “to continue being visible and outspoken about the march for equality.” Tim Cook will start receiving these letters, she predicted, and "will experience" the same thing.

When Baldwin first sought local office, in 1986, there were, she recalled, “just a couple dozen openly gay elected officials that we knew of in the world.”  Former Representative Barney Frank of Massachusetts, who was elected to Congress in 1980, publicly came out in 1987, and had no trouble being re-elected thereafter: he served 16 terms before retiring from Congress in 2013. Just before he left, in 2012, he became the first member of Congress to marry a same-sex partner while in office. Frank is always careful to note that he was not the first openly gay member of Congress, only the first to come out voluntarily. Four years before Frank declared he was gay, Representative Gerry Studds, a Democrat from Massachusetts, was caught in a scandal over his relationship with a 17-year old page.  He was censured by his colleagues in the House for misconduct with a subordinate. Studds contended the relationship was consensual, and was re-elected to the House six more times before retiring in 1997.

Baldwin applauded how many more openly gay people there are in politics today. “Now it’s in the many hundreds. That will only continue to change as there are more and more role models and more and more folks out there who prove who can be done.”

As for Frank, he spoke this morning to CNBC, and called Cook's coming out “extraordinarily important.” But despite his tone of celebration, he remarked that it was “wise” that Cook did not come out when he first took over at Apple. With this view, Andrew Sullivan, the popular blogger who has written extensively on gay rights, disagreed. He wrote to me by e-mail, "Barney is wrong, as usual. Any attempt to dodge the issue at any point in one's career perpetuates a culture of shame. So of course it's awesome he's now officially out. Better still that he sees it as a gift from God–exactly the right phrase to use."  

Bloomberg Businessweek editor Josh Tyrangiel, who edited the essay, told Bloomberg Surveillance that Cook's piece wasn't "precipitated by any event. It's not a reaction to anything." Tyrangiel acknowledged that Cook's coming out may be "slightly complicated" for Apple's business abroad but added that, historically, the "desire, and desire for their products, tends to trump prejudice."   

By coming out this morning, Cook became—easily—the most high-profile gay man in the world of corporations. As The New York Times noted, his move is in opposition to “corporate sexual identity norms; 83 percent of gay, lesbian and bisexual people hide aspects of their identity at work.”  It suggests, as former adviser to President Clinton Richard Socarides wrote for The New Yorker, "that gay rights is no longer an automatic wedge issue in American culture and politics." Clinton himself tweeted in support of Cook—"From one son of the South and sports fanatic to another, my hat's off to you, @Tim_cook"—joining the rush of corporate leaders like Richard Branson and Mark Zuckerberg expressing their pride, thanks, and congratulations. Yet while progress marches on, and same-sex marriage becomes legal in state after state—32, as well as Washington, DC—other pockets of the country remain resistant. Just days ago, at a ceremony inducting him into the Alabama Academy of Honor, Cook lambasted his home state for being “too slow on equality for African Americans. Too slow on interracial marriage, which was only legalized 14 years ago. And still too slow on equality for the LGBT community.”

For all the celebrities, artists, and other popular cultural figures who are out of the closet, very few gay corporate or political leaders have been public about their sexuality. In a story published this summer by Politico Magazine, Scott Evertz, who worked as George W. Bush's AIDS czar, describes thinking he was the only gay member of Bush's stuff. “I, of course—just by the law of statistics—knew that there were other gay people in the White House,” Evertz told Timothy Burger. “But not a single one of them was out to me, so I felt completely alone.”

I asked Baldwin why she thinks that there aren’t more openly gay people in American politics and American corporations—do these arenas somehow lag behind? She pointed out how different the domains are, in the first place.

“All my colleagues in the Senate answer to their constituents," she said. "We are there on equal standing, if you will–there’s not an employer in the traditional sense, who hires and fires.” That is, the conditions are unlike those of the corporate world. But, she added, “What I would note is that having a seat at the table matters.”

She told me of being elected to the House of Representatives in 1998, and how her sexual orientation helped shape her work. “When we were actually deliberating on issues like passage of the Matthew Shepard & James Byrd Jr. Act, my ability to connect with colleagues who had questions, who wondered about the potential impact of policy on LGBT community–the ability to sit down with colleagues and answer their questions, and bring my life experience to the job with me was very, very helpful. I see real benefit in seeing legislative bodies that look more like America, that are reflective of and diverse like America.” There’s benefit in corporate bodies looking more like America, too.