When she addressed the 2019 UN Climate Action summit in New York, Greta Thunberg, then just fifteen years old, was already an internationally recognised figure. “You all come to us young people for hope… How dare you!” she declaimed, scolding world leaders like an Old Testament prophet. “You have stolen my dreams and my childhood with your empty words!”

It was a powerful performance (albeit one that has since become the subject of online satire). She was named Time’s Person of the Year, and hailed as the voice of her generation.

But Thunberg’s activist focus has now moved on to other topics—as evidenced by her recent participation in a “freedom flotilla” to Gaza, which ended ingloriously when Israeli officials boarded Thunberg’s “selfie yacht” (as Israel derisively called it) and sent her packing. The whole stunt had an embarrassing quality to it; and emphasised the degree to which adulthood has erased Thunberg’s charm.

In a 2018 TED Talk, Thunberg said she didn’t want to become a climate scientist because “the climate crisis has already been solved,” and so “all we have to do is to wake up and change.” Also: “We can’t change the world by playing by the rules, because the rules have to be changed.”

This kind of sententious rhetoric would (or at least should) be seen as embarrassing if spoken by any educated adult. Yet Thunberg’s vapid pronouncements were seen as positively inspiring, because she was a teenaged girl speaking (it seemed) sincerely from the heart.

Now that she’s in her twenties, that excuse is no longer applicable, even if her supporters still imagine her locked in time as a sacred earth child (a secularised adaptation of that universal religious myth by which a boy or girl of unparalleled purity delivers salvation to an impure world). Her recent foibles serve as a cautionary tale regarding the dangers of mission creep among radicalised activists, and the unwholesome veneration of their hallowed saviour figures.

Thunberg was raised in the world of performing arts. Her father, Svante Thunberg, is an actor and producer named for an ancestral cousin who won the Nobel Prize in Chemistry. Her mother, Malena Emman, is an opera singer whose career brought the family to Berlin, Paris, Vienna, Amsterdam, and Barcelona; with summers spent in Glyndebourne, Salzburg, and Aix-en-Provence.

A sensitive child, Thunberg was reportedly traumatised at age eleven when her primary school teacher showed a video about climate change that depicted starving polar bears and flooded cities. After that, Emman reports, Greta cried constantly: “She was slowly disappearing into some kind of darkness and little by little, bit by bit, she seemed to stop functioning. She stopped playing the piano. She stopped laughing. She stopped talking. And she stopped eating.” (Thunberg chose to eat again, once her doctors and parents threatened her with hospitalisation and drip-feeding.)

While Thunberg is clearly terrorised by her fixations, they also fuel her apocalyptic fervour

Psychiatrists diagnosed the child with high-functioning autism (also known as Asperger syndrome), obsessive-compulsive disorder, ADHD, and selective mutism. Thunberg refers to these conditions as “superpowers” because they give her the ability to concentrate obsessively.

Put another way: While Thunberg is clearly terrorised by her fixations, they also fuel her apocalyptic fervour. “I don't want you to be hopeful. I want you to panic,” she told the World Economic Forum (WEF). “I want you to feel the fear I feel every day... I want you to act as if the house was on fire—because it is.”

Greta’s public activism began on 2 August 2018, when she skipped school on the first day of grade nine. Parking herself outside the Swedish parliament with a sign marked “School Strike for the Climate,” she handed out flyers that read, “I am doing this because you adults are shitting on my future.”