I spend a lot of time with teenage girls. Teenage girls who wear assiduously applied makeup every time I see them, and teenage girls in jeans and T-shirts who look as if they've never touched a mascara wand. And, occasionally, teenage girls more or less like the teenage girl I once was: usually barefaced, but occasionally glopping on such heavy liquid liner that they look like droopy-eyed raccoons. Sometimes we talk about their college visits or their weekend plans. They tell me about the semester they spent on a sailboat in the Caribbean or the Eric Garner protest their kick-ass social-studies teacher took them to. Sometimes they'll shyly ask whether I felt nervous about moving away for college, too. But mostly we talk about every teenager's least favorite subject (and the reason I'm there to tutor these girls in the first place): the SAT.

What doesn't change, across digressions and algebra equations, is the face I present to them. Never once in the past three years have I worn makeup to our tutoring sessions. Sure, I've had a few minor slips—times I haven't managed to wash the previous night's mascara from under my eyes and some observant girl has remarked, "Wow, you're wearing makeup." And I'll look at her and come up with a response that doesn't reveal my slight hangover or general lack of wherewithal on a Sunday morning: "I usually don't, but I just felt like it today."

They accept these excuses readily, as readily as they accept me. After all, not long ago I was one of them: another Manhattan-savvy high school kid, white and upper middle class with high-achieving parents and Ivy League aspirations. For them—for me—the makeup stakes aren't so very high. Even if these girls ink liquid swirls on their eyelids and heavy crimson bows around their lips, they'll always read more Lady Gaga than inappropriate or unhinged. They each enjoy the privilege that comes with the untempered beauty of well-kept youth. Their experimentations won't be judged too harshly, at least not yet. Especially when, in our world of Instagram portraiture, makeup's role as an acceptable and malleable brand enhancement has never been more pronounced. We're all makeup artists now.

Yet, despite my female students' high draw in the socioeconomic lottery and the fact that they attend progressive schools where the curriculum is gender-sensitive, they're often plagued by insecurities that rarely crop up among my boys: a lack of confidence with the unfamiliar, an anxiety surrounding the worthiness of their ideas, an almost pathological phobia of guessing for fear of being wrong. I recognize the unwillingness to be too smart, too bold, too self-assured. Bossy. Pushy. Shrill. As a feminist, I may have taken this dichotomy too much to heart. I've definitely told at least one student—only partly joking—that if she didn't start guessing on one particular standardized test, she would be "letting the patriarchy win."

And so it seems important—it has become important to me—not to wear makeup when I meet my students. As their 29-year-old tutor, I stand on shifting ground, somewhere between teacher and mentor, coach and friend, cheerleader and therapist. I remember my own adolescent years, those fitful days when a stray innocuous remark could fuel my spinning insecurities; the hours I spent wondering how I was supposed to look and how I was supposed to be; whether the popular guy in math class would ever notice me. (He didn't.) Among city kids, the male gaze extends far beyond the classroom; its weight is heavy on the streets and the subways—catcalls and wolf whistles are far easier to shrug off at 29 than at 13. A Manhattan girl is struggling early between wanting to disappear and wanting to be seen.

My students are learning what we all learn sooner or later: that the world will judge you by your looks. In not wearing makeup, I want to send a message to them, these avatars of my erstwhile self. You don't have to do it. You can look however you like. And both more obviously and most importantly, your appearance doesn't have to be your defining attribute. It's not a message that I'm certain any of them have heard—and not one I'd ever voice. There's no faster way to alienate a bunch of 16-year-old girls than by telling them how to dress or what to wear on their faces. Besides, I don't want to be one more person dictating how they should present themselves, or even remarking on their looks. But I present a possibility, in direct contrast to all the carefully coiffed and branded women they're seeing on Snapchat and YouTube and all the other image -crafting media they consume: all that decorating of your face that you may think you have to do—that's optional.

Of course, it's my own stuff that's informing this—my own relationship with makeup, with womanhood. It probably doesn't help that my first association with cosmetics was as an obligation. Makeup and my paternal grandmother were synonymous for me as a child. My father's mother was a Midwesterner who wore matching floral prints, and whose routine embodied the expression "putting on my face": caked foundation, rosy blush, blue eye shadow. She also owned a curling brush to keep her perm coiffed between visits to the hairdresser and would indulge my requests that she use it to curl my stubbornly straight hair. It was she who first warned me off makeup. She told me, when I asked, that there was no need. "I wear it because I have to," she'd say. "You don't need it. You're young."

I wore makeup in high school on rare and usually overdone occasions: thick black liquid eyeliner and dark-red lipstick. By the time I was 15, I'd already spent nearly 10 years with the same cohort of kids, and I was desperate to get away from them, to break from my childhood role of nerd and overachiever. Makeup was my ally, my lever out of that world and into others. The dark circles I began painting around my eyes announced that I was now artsy and edgy—druggy, even.

When one of the preppy boys told me I looked "coked out" (I wasn't), I felt positively vindicated. I put naïve and earnest effort into kindling that comment into rumor; I'd excuse myself from physics class for the purpose of returning twitchy, rubbing at my nose. When I bothered with cosmetics, it was almost purely to bolster this new sense of self: I wasn't that kid nearly jumping out of her chair to answer every question. I was a teenager, a writer, a member of the alternative set—with all of the attributes, real and occasionally falsified, that accompanied those labels. But my interest in actually wearing makeup—and certainly wearing it as my grandmother did, as a sort of daily ablution—remained fitful at best. More often than not, I lacked the time and energy to apply eyeliner before grabbing my backpack and stumbling out the door at 7:30 in the morning. Yet my sporadic accentuation of my eyes made enough of an impression for one acquaintance, years later, to offhandedly describe my social circle as "goth."

In college, contrary to what the scribes of Clueless would have predicted (Tai's voice echoes in my head: "College girls wear less makeup on their face," and forever begs the question, As opposed to where?), makeup became an ever-so-slightly more regular part of my routine. I fell in with a cooler crowd, girls who knew what clothes to wear and how best to angle their faces in photographs. A glamorous British friend with luscious blond hair past her waist and perfectly lined blue eyes would artfully paint my face before we went out together. We bought low-cut shirts and miniskirts from the cheap shops on Chapel Street in New Haven and took pictures of each other striking our most sultry poses, lips parted, eyes wide. And as we snuck into bars on borrowed IDs, I felt sexy, sophisticated.

I graduated and moved, predictably, to Brooklyn, where my first grown-up boyfriend told me he liked me better without makeup—and I liked me better that way. In retrospect, there was a sort of hubris there, too, in the not needing to wear makeup. Just like my grandmother said, though it was an acknowledgment not just of youth, but of prettiness too. Makeup hides flaws, right? By the time I started tutoring—at 26, after I quit my job as an editor at Salon.com to write a novel about Cleopatra and her sisters that, three years later, will be published this month—it wasn't something I thought much about. I associated makeup with my younger self, with an almost childish conception of what a woman looked like.

At some point, all that changed. For one, after a two-year hiatus, I decided to try dating again in earnest—and lined up five OkCupid dates in one week before swearing off the entire enterprise for months in a fit of pique. One of the guys, a never-married forty-something novelist with all the commitment issues that description evokes, didn't bother to cloak his preferences in faux-feminist proclamations. Instead he lamented the fact that I didn't wear enough makeup, that I never got dolled up to go out. "Can't you do smoky eyes?" he'd plead. I found the request maddening, but I did appreciate his honesty after years of trying to negotiate the classic trap, so brilliantly skewered by Amy Schumer: Men claim to prefer women barefaced…while expecting us to look flawlessly done-up.

Meanwhile, as I worked on my book, Cleopatra's Shadows, I was delving into a world—Ptolemaic Egypt—where a woman's clothing and cosmetics took on much higher stakes. Appearance could mark the difference between life and death, power and insignificance. Cleopatra still looms large in our imagination. Even if she didn't have Elizabeth Taylor's natural beauty (and many ancient sources suggest she didn't), she certainly had her style, charisma, and flair for the dramatic. Plutarch's description of the Egyptian queen sailing to meet Antony for the first time always sticks in my mind: On a barge with violet sails, Cleopatra lay beneath a golden canopy "dressed as Venus in a picture" with "beautiful boys like painted Cupids" standing on either side. Here was a woman who, definitively, knew how to present herself. And soon, I had to figure out how to do so myself. My writing began to demand action beyond pajama-clad slouching over a laptop in my living room. I needed to reconnect with various people from my business past—I needed to meet agents and an editor. I had to, in short, look like a grown woman.

As someone who had never paid much attention to clothes, who had managed to maintain a wardrobe of hand-me-downs and college-era T-shirts, I found this prospect daunting. In some ways, the easiest part was the makeup. I already owned some very pricey cosmetics, in fact, the remnants of a most unlikely internship at a French fashion magazine in Paris during college—and it was easier (and cheaper) to procure new lipstick than a whole new set of clothes. My first goal was simple: At least 20 percent of the time when I left the house, I wanted to look like the adult female I imagined I was supposed to be.

And here, of course, my two worlds start to collide: the world in which I'm (aspirationally?) an inspiration to teenage girls—how to stand up to the system and branding imperatives, how to wear your face bold and bare—and the one in which I'm desperately trying to prove, be it to publishers or eligible bachelors, that I am a 29-year-old who knows how to wear good clothes and do a smoky eye. Someone who has figured out how to be a professional woman in the world.

That feels like something I should have already figured out. Perhaps it's because I'm a millennial, the boomerang generation still struggling to claw its way out of its parents' collective basement. After all, Cleopatra was in her late twenties when she wowed Antony in the guise of Venus, on her road to empire building. And, nearer to my own experience, my mother had a three-year-old by the time she was my age. She might not have worn much makeup, but she certainly knew what it meant to be an adult.

I try to schedule my different selves on different days—not to do publishing business on the days I tutor, not to date on the days I tutor—but this is proving to be virtually impossible. Instead the subway becomes my dressing room, and I flout the new MTA ads decrying "clipping" and "primping" on the train. I balance a small mirror on my knee as I pull down my lower lid to apply eyeliner; I carry removal wipes to get rid of the black remnants of mascara. I am constantly shifting spheres, shifting spaces between the woman I once thought I should be and the woman I'm trying to project.

In the end, I realize, my aversion to makeup is just as controlling as an addiction to it. I should just wear it if I want to. Or not, if I don't. Makeup can be fun, refreshing: the excitement of putting on a different mask, a different face, a different you. The fact that it has taken on so much psychic space in my life has as much to do with me as it does with societal pressures. At 18, I was sure that wearing all that makeup made me look like a grown-up. At 23, I was sure that not wearing all that makeup made me look like a grown-up. At 29, I'm sure that the only way I can look like an adult novelist is by dabbing on a subtle streak of eyeliner, a light fringe of mascara, and some lipstick. Enough to brighten my face, but not so much that anyone would notice. In short, makeup that makes me look like I'm not wearing makeup.

The real problem—beyond the makeup—is that I still feel like I'm flailing when it comes to presenting myself. And so I use makeup to draw lines around my changing selves.

I should take a page from Cleopatra; she was the ultimate unconflicted manipulator of costumes and appearances. As a Hellenistic queen ruling an Egyptian kingdom in a Rome-dominated world, she had to juggle personae to shock and awe her various audiences and conquests. To ensure her legitimacy with the native population, she evoked the pharaohs of antiquity, whose lin eages had died out some thousand years before her time. And so, at her coronation in Memphis, Cleopatra would have likely dressed in bright white linen and a jewel-encrusted ceremonial wig, upon which a shaven priest placed the red-and-white double crown of Upper and Lower Egypt. At home in Alexandria, Cleopatra paraded about the city in the highest Greek fashions: her hair swept up in a bun, braided and decked with pearls; her brightly colored tunics cinched with a jeweled brooch or a girdle, the finest ones cut from expensive Chinese silk. To complete the image, she would have worn the traditional Hellenistic diadem, a white ribbon to hark back to the rule of Alexander the Great, upon whose legacy her family staked their claim.

Of all her audiences, the Romans were the toughest to enchant. While her lovers Caesar and Antony were enthralled by Cleopatra's elaborate guises, the staid statesmen of the city decidedly weren't buying it. With little role in public life, Roman women were expected to be demure, almost invisible. An exotic, assertive queen sleeping with Rome's most powerful general shook the city to its core—her look, even toned down for Roman sensibilities, could not have helped. The famed Cicero put it most succinctly; after their first meeting at Caesar's villa, he wrote, quite simply, "I detest the queen."

Happily, my struggles and those of my girls to win favor before our competing audiences don't involve political—or actual—survival. I'm sure most of the students I tutor don't care whether I wear makeup or not. It's my internal battle, not theirs. But if they think back on me 10 years from now, what I want them to remember—other than how I helped them rock their SATs—is, She helped me realize I could present myself however I wanted to be.

This article originally appears in the November 2015 issue of ELLE.