"Lean in." The phrase has become a part of the modern American workplace, largely because it was the title (and the main message) of Facebook COO Sheryl Sandberg's 2013 mega-bestseller.

But it's also been criticized for being a little tone-deaf and dismissive of working women whose circumstances don't allow them to "lean in."

You probably know what happened to Sandberg--namely, that she lost her husband, Dave Goldberg, two years after she published Lean In. Now she's out with another book, Option B: Facing Adversity, Building Resilience, and Finding Joy.

It's well-written. I can't imagine the pain of losing the love of one's life. But besides the larger message, Option B contains two short sentences that hold great power:

"They were right. I didn't get it." (emphasis in original).

The audacity of admission.

Sandberg is the second-in-command at what's probably the most impactful company of the past decade. Forbes estimates her net worth is north of $1.5 billion. Having never met her, I can't say for sure--but it would seem she has maximized her opportunities.

And to be sure, she's had a lot more opportunities than most people have. There's a phrase that a talented writer once coined, talking about a politician: "Born on third base, thinks he hit a triple."

Is that fair here? I'm not sure, but Sandberg's parents were successful. She graduated from both Harvard University and Harvard Business School. She was an early employee at Google, and has been Mark Zuckerberg's right hand for nine years.

All of that is why it's hard for a lot of people to swallow her advice on how to become successful, especially as a woman in business. It's easy to preach "lean in," in short, when you've got a lot of other people (and perhaps, the weight of the world) leaning in with you.

But then, she lost her crucial person. And, she says, she began to see how others perceived her advice. It took courage to boil that down succinctly into seven key words.

"Make your partner a real partner."

Here's the key passage in context:

"When I wrote Lean In, some people argued that I did not spend enough time writing about the difficulties women face when they don't have a partner. They were right. I didn't get it. I didn't get how hard it is to succeed at work when you are overwhelmed at home.

I wrote a chapter called, 'Make Your Partner a Real Partner,' about the importance of couples splitting childcare and housework 50/50. Now I see how insensitive and unhelpful this was to so many single moms who live with 100/0. ... Working moms, especially those who are single, are put at a disadvantage from the start."

"They were right. I didn't get it."

I think those seven words can go a long way toward bridging the gap between those who recoiled against Lean In and those who find value in Option B.

A TED talk apart.

I don't think Sandberg and Pope Francis have ever met, but they have at least one thing in common: as of this week, they've both given TED talks.

(Sandberg gave one that ultimately became the basis for Lean In; the pope gave a surprise TED talk just this week.)

And maybe because I read Option B at basically the same time that I watched the pope's talk, I found some similarities between them. The first is that the pope's talk was largely about encouraging people in science and technology to use their discoveries in the furtherance of bringing people together.

But the second is more basic. It's that the most important component in pursuing happiness in life is to develop authentic relationships.

That's at the core of both Sandberg's and Pope Francis's messages--and the sentiment behind Sandberg's seven words. It takes courage to take that rhetorical step.