The public visibility of socio-political campaigns surges and recedes, often with little relation to the importance of the issue they focus on.
Not much more than a year ago, back when large public assemblies were not considered potentially lethal weapons, millions of people gathered around the world to call for action on a fairly important matter: climate change.
Like many campaigns, this one didn't have a single leader.
If it had, it might have been Greta Thunberg, a Swedish teenager with autism (Asperger's) and an unshakeable conviction that we are destroying the world in which she hopes to grow up.
I Am Greta, a feature-length documentary available on Hulu, traces Thunberg's story, which is remarkable by any measure.
In August 2018, she was an introverted 15-year-old who decided to sit outside the Swedish parliament with a single hand-made sign that said she was on strike from school until Sweden's leaders addressed climate change in a meaningful way.
A year later, she was the face of a movement, primarily young people, pushing that demand on leaders all over the world.
She addressed the United Nations. Pope Francis arranged to meet her. Donald Trump mocked her at MAGA rallies, where he called climate change a "hoax."
She reacted to Trump more maturely than he reacted to her, essentially shrugging him off. While she doesn't talk about it specifically in I Am Greta, viewers get the idea she had encountered worse cruelty in her own school years, when classmates mocked her autism and Asperger's (Autism Spectrum Disorder). Trump, in contrast, was mostly trying to score political points.
By any measure, and whatever her original aspirations, Thunberg's campaign scored. She helped bring the issue to the forefront with the generation that will have to live with its consequences. If most campaigners aren't as focused and persistent as she, there's still an increased ongoing awareness that can't help having a positive impact.
Interestingly and perhaps most significant, though, neither Thunberg nor I Am Greta frame her achievements as a big win.
On the contrary, Thunberg repeatedly expresses frustration not only with the Trumps of the world but with more sympathetic leaders that she accuses of saying the right things and then doing nothing.
When she spoke to the UN's world climate change conference in New York in August 2019 (top), she told the assembled group – which by definition was addressing the issue – that it should be ashamed of itself.
"You have stolen my dreams with your empty words," she said. "How dare you?"
This echoes her earlier observation that getting invited to castles and palaces and great meeting halls had been more depressing than flattering.
She was showered with praise for her courage and conviction. She was told to keep up the good work. "And then," she says, "they do nothing."
I Am Greta touches briefly on the genesis of her campaign. She saw a film in school, she says, that showed dying ecosystems and starving animals. She read the broad consensus among scientists that climate change is accelerating and must be addressed immediately to mitigate its impact.
So she drew her sign, loaded her backpack, and sat down against a grey, stone wall outside parliament. After a few days, she attracted some notice, and things went from there.
Late scenes in the film show Thunberg reading some of the vile and threatening comments posted about her on various news and social media platforms. She seems unbothered as if she recognizes this is an inevitable consequence of taking an aggressive public stand.
Still, it's hard to imagine what it would be like, at the age of 15 or 16, to get that level of attention over something you don't see as controversial at all. Who could be against preserving the planet?
As she became known, Thunberg developed a polite public persona. She greeted and thanked people who lined up to meet her at rallies. She was cordial to officials who wanted to see her, even if she was frustrated at what she considered their inaction. She posed for a constant stream of selfies.
After months of that, it's no surprise she looks most relaxed when she's back in Stockholm, cuddling up with the family's black Lab or patting one of the horses.
Still, one effect of Asperger's is that it can make you focus relentlessly on something you consider important, and there's no sign Thunberg intends to move on to anything else before the world starts taking concrete steps to save itself.
She started as a girl with a sign. That girl is still on the case.