Democratic presidential candidate Hillary Clinton speaks during a presidential primary election night rally, Tuesday, June 7, 2016, in New York. (AP Photo/Julio Cortez)

Hillary Clinton cracked another glass ceiling this week, reaching the number of delegates needed in the Democratic primary race to become the first female presumptive presidential nominee of a major political party.

Again and again, she and her campaign made allusions to that famous image about women's advancement as they marked the memorable milestone, with Clinton saying in a speech Tuesday night "this campaign is about making sure there are no ceilings, no limits on any of us." She noted "we are standing under a glass ceiling right now," referring to the building in Brooklyn, N.Y., where the rally was taking place.

A Clinton fundraising email sent Tuesday said "we broke one of the highest, hardest glass ceilings in America," harking back to the famous line from her 2008 concession speech, when she said that invisible upper barrier may not have been shattered, but now has "about 18 million cracks in it." Of course, there was a hashtag: #HistoryMade.

As Clinton reaches this historic moment, she's again embracing the influential metaphor that for decades has symbolized the struggle women face to reach the top levels of power. Yet 30 years after it first came into widespread use, how apt is it today? How did it first become such a powerful metaphor for bias in the workplace? And does it still really illustrate the problems women face, or does fatigue over the phrase -- particularly one that may not apply to all women -- obscure their challenges instead?

The origins of the now ubiquitous metaphor aren't entirely clear, though a couple of references in books and news articles appear to be what first made it well-known. In 1986, the Wall Street Journal published a special report called "The Glass Ceiling" by Carol Hymowitz and Timothy Schellhardt that helped launch the phrase into popular use. But two years earlier, Gay Bryant, then the editor of Working Woman magazine, used it in a quote in Adweek, as well as in a book she edited titled "The Working Woman Report: Succeeding in Business in the '80s."

The 1984 book says that "Partly because of continuing, though more subtle, discrimination, a lot of women are hitting a 'glass ceiling' and finding they can rise no further." (One hot tip from the book: "The dress-for-success wardrobe for women" includes a "man-tailored, dark colored, traditionally designed skirted suit;" putting on "the uniform also signals that you are serious about business.")

Reached by phone Wednesday, Bryant, now retired and working on a memoir, said she does not claim to have coined the phrase, and that she might have gotten it from study mentioned on the same page as the above quote, by Anne Harlan and Carol Weiss of the Wellesley College Center for Research on Women.

"In my chapter it's there in quotes," she said. "I popularized it, but where it actually comes from I don't know." Another story in the Wall Street Journal last year about the origins of the phrase pointed to an even earlier conversation between two female Hewlett-Packard executives, one of whom said she presented the glass ceiling concept at a 1979 conference of the Women's Institute for Freedom of the Press.

However it started, it not only stuck, but spawned an entire vernacular of metaphors about the challenges women and minorities face in the workplace. Today, we have the "glass cliff," used to describe the disproportionate number of times women seem to be put into difficult leadership opportunities. We have the "maternal wall," or the career limitations that result from stereotypes of working mothers. There are "glass escalators" (which describe how men in female-dominated occupations get promoted more rapidly) and even "sticky floors" (used either to depict either the challenges women face in getting out of low-paying jobs or the limits women impose on themselves).

That's hardly all. The "ceiling" metaphor has been deployed for the challenges women and minorities from many groups face: There is a "bamboo ceiling," referring to barriers people of Asian descent face. A "stained glass ceiling," for the limitations encountered by women in religious leadership roles. Even a "perspex ceiling," which alludes to the obstacles for women in the manufacturing industry, using the trademark for acrylic resin that can be used as a substitute for glass.

There's been such a proliferation of piggybacking phrases that a 2012 paper by three professors in Australia titled "A maze of metaphors around glass ceilings" attempted to chronicle them.

"The apparent contradiction between the plethora of glass ceiling related metaphors and the slow rate of increase in the proportion of women as leaders," the authors wrote, "suggests that even memorable metaphors based on extensive empirical research are doing little to help counter the perception that women are not made of the 'right stuff' for leadership."

Some believe the growth of such phrases showcase the power of the metaphor. "I think the idea of a glass ceiling -- it just really captures people’s experience," said Joan Williams, the director of the Center for WorkLife Law at the University of California Hastings College of Law, in an interview. Women think "I’ve done everything right, but now I’ve hit the ceiling, and I just see the men sailing past it." 

Yet others have asked how useful the phrase remains -- saying that calling it a "firewall" or a "labyrinth" might be more fitting. Writing in the Harvard Business Review about their 2007 book, "Through the Labyrinth," professors Alice Eagly and Linda Carli wrote that the "glass ceiling metaphor is now more wrong than right." For one, it describes barriers that have been broken -- for instance, we now have women who are Fortune 100 CEOs, even if in very small numbers. Yet it also implies that women and men have equal opportunity at lower levels, that women are somehow unaware of the obstacle, and it doesn't reflect the complexity of challenges women face throughout their careers.

Still others say the phrase "glass ceiling" applies more to well-educated white women than to others. "The term we’re hearing a lot from young women of color is the 'concrete ceiling,' " said Sylvia Ann Hewlett, the economist and founder of the Center for Talent Innovation, in an interview. "They very much object to the idea that you can see through this ceiling. For them, it’s thoroughly opaque and seemingly unbreakable." 

But even if "the glass ceiling" could use an update, or isn't the best phrase for all people, that doesn't mean it isn't still a powerful image to help shape the story of the barriers some women face. "The 'glass ceiling' is actually a very rich metaphor," Hewlett said. "I do think that’s why it’s stayed around." She believes "the reason there is a little metaphor fatigue isn't so much because they're bad metaphors or fail to illuminate the situation, but there's something depressing and distressing about the fact that we haven't shifted the numbers any more." 

In other words, even if Clinton does win the presidency and ultimately shatters that "highest, hardest glass ceiling," we'll likely still be talking about it, as well as the glass cliffs female leaders get pushed off, the sticky floors that trap some women, and the concrete ceilings women of color may face. And we should. If metaphors "are part of the storytelling that can compel change," as Eagly and Carli wrote, we're going to need plenty of them.

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