Walt Whitman saw in trees the wisest of teachers and Hermann Hesse found in them a joyous antidote to the sorrow of our own ephemerality. “The tree which moves some to tears of joy is in the eyes of others only a green thing which stands in the way,” William Blake wrote in his most beautiful letter. “As a man is, so he sees.”

Many tree-rings after Blake and Whitman and Hesse, another visionary turned to trees as an instrument of civil disobedience, empowerment, and emancipation, advancing democracy, human rights, and environmental justice.

Born near a holy fig tree in the central highlands of Kenya twenty years after the country became a British colony, Wangari Maathai (April 1, 1940–September 25, 2011) went on to become the first African woman to win the Nobel Peace Prize, awarded for her triumph of promoting “ecologically viable social, economic and cultural development” by founding the Green Belt Movement responsible for planting 30 million trees and empowering women to partake in social change — an act of courage and resistance for which she was beaten and imprisoned multiple times, but which ultimately helped defeat Kenya’s corrupt, authoritarian president and blazed a new path to ecological resilience.

French children’s book author Franck Prévot and illustrator Aurélia Fronty tell her remarkable story in Wangari Maathai: The Woman Who Planted Millions of Trees (public library) — a lovely addition to the most inspiring picture-book biographies of cultural heroes.

Growing up in a small hut with walls made of mud and dung, Wangari watched the British colonialists grow richer and richer by cutting down trees to plant more tea. She ached to see the trees fall, but didn’t yet know that she had the agency to stand up for them and for her people.

One day, with the simplicity and sincerity of a child’s enormous question, her older brother asked the family why he was allowed to go to school and learn, but Wangari was not. And, just like that, the unquestioned cultural more that girls must remain at home until they marry and have a family of their own unraveled. Their mother made the radical decision to answer her son’s question with action and enrolled her daughter in the village primary school.

At eleven, Wangari left home to study at a boarding middle school run by Italian nuns. She graduated from high school at a time when very few African women learned to read at all. In September 1960, then-senator John F. Kennedy initiated a program that welcomed promising African students to study in the United States. Of the entire continent, only a few hundred young people earned such an invitation. Wangari Maathai was among them.

She arrived in America to discover with shock that even in a country as wealthy and emblematic of freedom, human rights were not equally apportioned. She witnessed the height of the civil rights movement just as her own country was finally winning its independence from British rule.

And yet upon returning to Kenya, she found that trees were no better off — colonialism had crumbed, but it had left in the rubble a nation so impoverished and dependent that Kenyans were forced to continue cutting down trees just as the British had, selling the lumber and using the felled land to plant tea, coffee, and tobacco for export. As marine biologist and author Rachel Carson was making ecology a household word across the Atlantic and issuing the radical insistence that the real wealth of a nation “lies in the resources of the earth — soil, water, forests, minerals, and wildlife,” Wangari Maathai was realizing that her nation’s welfare depended on healing the broken relationship between a broken economy and a broken ecology. She came to see that a tree is much more than an economic resource. She came to see, in Prévot’s lovely words, that “a tree is a little bit of the future.”

Progress, however, is slow. “The longer the lever the less perceptible its motion,” Thoreau — the patron saint of trees and civil disobedience — wrote in contemplating the long cycles of social change. In 1977, three decades into her outrage, Maathai founded the Green Belt Movement and set out to plant trees all over Kenya, traveling to villages and encouraging people to think about the future, whatever the privations of the present may be.

Her insistence on women’s leadership was nothing short of countercultural in a society where women were expected to demur and lower their gaze in the mere presence of a man. And yet she persisted, entrusting tree nurseries to local women and seeding in them a newfound sense of civic agency. She herself stood up to the president himself, who had initiated a massive real-estate development in the city’s precious urban forest, habitat to endangered species like the blue monkey and the river hog, and had endeavored to build a skyscraper and a statue of himself in the heart of Nairobi’s largest park.

In response to the lengthy protests she organized, for which she was imprisoned several times, the government forced Maathai out of her office, calling her “a crazy woman” in press statements and describing the Green Belt Movement as “a bunch of divorcees.” (Meanwhile in America, Rachel Carson was enduring the same sexist assaults from government and industry, who painted her as a hysterical spinster for her composed, courageous, scientifically rigorous exposé of the pesticide industry that would catalyze the environmental movement.)

But Maathai persisted, alerting leaders around the world to the ecological and human rights abuses in her country. In letters and speeches, her voice reached beyond the government-controlled echo chamber of the Kenyan press, igniting an international investigation that eventually made the president relinquish his exploitive development plans. Upon her triumph, a man from rural Kenya greeted her during one of her village visits with these words: “You are the only man left standing.”

Over and over, the president tried to fell Maathai and her movement. In a desperate bid for control, emblematic of Hannah Arendt’s insight into how tyrants use isolation and separation as a weapon of oppression, he attempted to set neighboring tribes against one another. But Maathai and the Green Belt Movement built a simple, brilliant bridge across this artificial divide — they offered saplings from tree nurseries as tokens of peace to be exchanged between tribes.

Eventually, Amnesty International and UNESCO published a report exposing the president’s corruption and human rights abuses, ending his quarter-century reign. Maathai — by that point affectionately known as Mama Miti, “the mother of trees” — was elected to the new Parliament and appointed Assistant Minister of the Environment, Natural Resources, and Wildlife.

On October 8, 2004, midway through her sixty-fifth year, she was awarded the Nobel Peace Prize. By the end of her life, the movement she started had planted thirty million trees, reimagining the ecological and economic landscape of possibility for generations of Kenyans to come, and modeling for the rest of the world a new form of civic agency standing up for nature and humanity as an indivisible whole.

Complement the immensely inspiring, gorgeously illustrated Wangari Maathai: The Woman Who Planted Millions of Trees with this Krista Tippett’s wonderful On Being conversation with Maathai, then revisit philosopher Martin Buber on what trees teach us about being human and ecologist Lauren Oakes on what one endangered tree species can teach us about grace and resilience.

For other heartening picture-book biographies of visionaries who have changed this world, savor the illustrated stories Jane Goodall, Jane Jacobs, Ada Lovelace, Louise Bourgeois, John Lewis, Frida Kahlo, E.E. Cummings, Louis Braille, Pablo Neruda, Albert Einstein, Muddy Waters, and Nellie Bly.