I read the book Frankenstein before watching any film adaptation. In fact, I read it way before watching any film adaptation; I was eight years old and really had no business reading it. The description of the monster’s yellowed skin, thin black lips, and haunting eyes filled my nightmares for months, and when I finally reread the book in college, I kept the lights on. Frankenstein’s monster will always unnerve me, but perhaps his creator is an even greater monster.

Spoilers ahead for a 200-year-old book.

Mary Shelley’s Frankenstein depicts medical student Victor Frankenstein’s descent into insanity as he plays god and then must reckon with his twisted creation. On seeing his handiwork lurch to life, Victor is repulsed, and the resulting feud between creator and creature drives the remainder of the novel. In agony after the young scientist refuses to build a mate for him, the lonely nameless monster murders those closest to Victor and chases him into the frozen wilderness. Victor takes ill and makes his way to a stranded ship, where he recounts his tale to the ship’s captain before succumbing to his sickness. Victor’s last words are a caution: avoid ambition. The creature arrives to pay his respects (acknowledging, without his maker, he is now forever alone) and vanishes into the night.

Many of the tropes we now associate with the Frankenstein story arose in later theatre and film adaptations. For example, the use of electricity in the reanimation process is completely absent from the novel; as Victor is the narrator in that portion, he leaves out the details of his formula for life (lest someone else read the account and attempt to replicate his experiment). The hunchbacked Igor and the classic “IT’S ALIVE!” scream also appear nowhere in the novel, and the convention of calling the monster “Frankenstein” came along much later as well. As for the green skin, neck bolts, and flattop haircut, they entered the pop culture ethos with Boris Karloff’s iconic portrayal of the creature in the 1931 film. In more recent years, the green skin and neck bolts mostly accompany more comedic portrayals (Young Frankenstein, Herman Munster, Frankenberry, etc.), while more serious attempts like the 1994 Kenneth Branagh film, Penny Dreadful, the 2015 film, and Blade Runner (yes, really) stay truer to the monster’s depiction in the novel. Ultimately though, it’s not the monster’s physicality that sparks the greatest terror; it’s the twisted motivation behind his creation.

Mary Shelley gave her novel the alternate title The Modern Prometheus, a callout to the tortured benefactor of humanity from Greek mythology. Victor’s ambitions draw him into the Prometheus role, and like the titan, it results in his torment. On the other hand, the monster reads a different parable of ambition during his time in hiding: Milton’s Paradise Lost, the story of the fall of Lucifer due to his toxic ambitions. Walton (the ship captain) gets stuck in the ice due to ambition. There’s ill-fated ambition all over the place in this story. The real horror here is not some monster stepping out of the night to do us harm; it’s the notion that we might create our own downfall. That’s why Victor is so tortured. That’s why the novel and films generate that sickened feeling in our stomachs. When done right, Frankenstein invites us to think:

What if all the wonders we’re creating
—the scientific advances,
the modern medical marvels,
the technological revolutions,
the steady march toward near-immortality—
what if these ambitions push our humanity to the periphery,
and we wind up the unwitting makers of our own damnation?
What if the real terror,
the terror that leads to our downfall,
is something we ourselves create?

That’s why Frankenstein is scary.