No one can agree.

She's the mysterious subject of Dutch master Johannes Vermeer's "Girl with the Pearl Earring," a painting often referred to as the "Mona Lisa of the North."

Belonging to a Dutch style of idealized, sometimes overly expressive paintings known as "Tronies," the "Girl with the Pearl Earring" has the allure and subtlety characteristic of Vermeer's work.

But this painting stands apart from the quiet narrative scenes that we observe from afar in many of Vermeer's paintings.

"A Girl Reading a Letter"

"A Piano Lesson"

"A Portrait Artist at Work"

These paintings give us a sense of intimacy while retaining their distance.

A drawn curtain often emphasizes the separation.

We can witness a milkmaid serenely pouring a bowl of milk, but that milk isn't for us.

We're only onlookers.

The studied composition in Vermeer's paintings invokes a balanced harmony.

With the checkered floor in many of his works, Vermeer demonstrates his command of perspective and foreshortening.

That's a technique that uses distortion to give the illusion of an object receding into the distance.

Other elements, like sightlines, mirrors, and light sources describe the moment through space and position.

The woman reading a letter by an open window is precisely placed so the window can reflect her image back to the viewer.

Vermeer would even hide the leg of an easel for the sake of composition.

The absence of these very elements brings the "Girl with the Pearl Earring" to life.

Vermeer's treatment of light and shadow, or chiaroscuro, uses a dark, flat background to further spotlight her three-dimensionality.

Instead of being like a set piece in a theatrical narrative scene, she becomes a psychological subject.

Her eye contact and slightly parted lips, as if she is about to say something, draw us into her gaze.

Traditional subjects of portraiture were often nobility or religious figures.

So why was Vermeer painting an anonymous girl?

In the 17th century, the city of Delft, like the Netherlands in general, had turned against ruling aristocracy and the Catholic church.

After 8 decades of rebellion against Spanish power, the Dutch came to favor the idea of self-rule and a political republic.

Cities like Delft were unsupervised by kings or bishops, so many artists like Vermeer were left without traditional patrons.

Fortunately, business innovation, spearheaded by the Dutch East India Company, transformed the economic landscape in the Netherlands.

It created a merchant class—a new type of patron.

Wishing to be represented in the paintings they financed, these merchants preferred middle-class subjects depicted in spaces that looked like their own homes surrounded by familiar objects.

The maps that appear in Vermeer's paintings, for example, were considered fashionable and worldly by the merchant class of what is known as the Dutch Golden Age.

The oriental turban worn by the "Girl with the Pearl Earring" also emphasizes the worldliness of the merchant class, and the pearl itself, a symbol of wealth, is actually an exaggeration.

Vermeer couldn't have afforded a real pearl of its size.

It was likely just a glass or tin drop varnished to look like a pearl.

This mirage of wealth is mirrored in the painting itself.

In greater context, the pearl appears round and heavy, but a detailed view shows that it's just a floating smudge of paint.

Upon close inspection, we are reminded of Vermeer's power as an illusion maker.

While we may never know the real identity of the "Girl with the Pearl Earring," we can engage with her portrait in a way that is unforgettable.

As she hangs in her permanent home in the Mauritshuis Museum in The Hague, her presence is simultaneously penetrating and subtle.

In her enigmatic way, she represents the birth of a modern perspective on economics, politics, and love.