The hills of Kenya were turning brown. Deforestation had been a problem going back to the colonial era when people were forced off the land, and forests were turned into tea plantations. With independence in 1963, Kenya’s new leaders continued selling timber and clearing forests for their own tea plantations. There were fewer and fewer trees, and people’s traditional connections with nature were lessening. One woman, Wangari Maathai, wanted to change that.

Maathai was born in Kenya’s central highlands in 1940. As a young woman, she won a scholarship to attend a small college in Kansas, part of the “Kennedy airlift” that enabled about 300 Kenyans—including Barack Obama’s father—to study in America. She became the first woman to earn a doctorate at the University of Nairobi. But despite her achievements she was troubled: “I kept stumbling and falling and stumbling and falling as I searched for the good.” A question resounded in her head: 

“Why?” I asked myself. . . . others told me that I shouldn’t have a career, that I shouldn’t raise my voice, that women are supposed to have a master. That I needed to be someone else.

She started a business and then a non-profit to plant trees, but both failed. In 1977, she started the grassroots Green Belt Movement to teach rural women to plant trees and help them understand the deep connection between the life of trees and their own lives. In 1992,  government thugs beat her unconscious, and the government put her name on a list of activists targeted for assassination. But she kept on, and her movement grew. In 2004, she won the Nobel Peace Prize.

Maathai died of ovarian cancer in 2011, but the movement she began has planted tens of millions of trees in Kenya and inspired countless people, including a global campaign to plant a trillion trees to fight climate change. As with many visionary leaders, she looked not only to the past but also to the future—in her case, thanks in part to her American college experience: “America changed me in every way. I saw the civil rights movement. It changed what I knew about how to be a citizen, how to be a woman, how to live.”

Her life reveals the heart of leadership: the courage to ask simple but profound questions, like ‘why,’ that help groups confront and tackle their biggest problems. That’s leadership in a nutshell.

Of course, that simple definition of leadership leaves out many vital tasks—how leaders discern the path ahead, how they rally support, how they overcome doubts, how they maintain discipline when enthusiasm fades, how they react to a thousand unexpected shocks and changes, how they transform entrenched self-interest into collaborative energy. But it gets to the heart of what leaders do: they push groups to solve their biggest problems by asking the right questions. 

Leadership as problem-solving is separate from the two major devices humans have already created to solve problems that groups face: culture and bureaucracy. Culture is an evolutionary adaptation made possible by our highly developed cognitive and social learning skills. A group’s culture helps it remember and apply the lessons of the past: choices and actions that helped it endure. These become the beliefs and teachings that stamp new members with old wisdom. 

Culture remains a powerful force. In a world pulsing with change, billions of people hold their traditional beliefs and teachings as their bedrock for living meaningful lives. Many yearn for leaders who promise the restoration of an idealized past. Around the world, leaders have stepped forward, claiming the ability to do just that, to varying acclaim and success. Perhaps the most interesting contemporary example is India’s popular Narendra Modi, unabashed in his elevation of fervent Hindu nationalism and culture.

Bureaucracy solves a group’s problems in a different way. Instead of drawing wisdom from the past, bureaucracy values only one kind of knowledge: rational knowledge. It seeks to measure and classify everything, establish rigid structures and roles, and bring (and rely on) rules that regulate how work is done. The sheer accumulation of records and rules eventually makes initiative and innovation harder. And the impersonality of bureaucracy, its defining trait, left to its own logic, sucks the life out of human interactions.

Both culture and bureaucracy are powerful systems for helping groups solve problems. Wangari Maathai built her Green Belt Movement on a bedrock of traditional Kenyan cultural values about identity, place, and nature. Florence Nightingale, in 19th century England, revolutionized the use of statistics and meticulous bureaucratic research to reduce mortality among wounded soldiers in the Crimean War. She devoted her whole life to this work, in the process largely inventing the field of epidemiology and, in later decades, using careful records and measurements to combat illness and poverty and establish scientifically-based nursing education, initially for women.

But neither culture nor bureaucracy, by itself, can solve all the problems that groups face in the modern world. Both struggle to deal with radical change. That is why leadership matters more today than ever before. Human beings have never existed in a world more frequently rocked by radical, transformative change—mostly brought upon us by our own actions (climate change), economic activity (global capitalism), and restless curiosity (technological disruption). That is why Kenya needed a Maathai, and why today so many groups cry out for leadership.

Leaders inspire, motivate, challenge, drive innovation, and overcome resistance. But before all that, like Maathai asking ‘why,’ or Florence Nightingale in 1855 asking “my immense first question, how this hospital is to be purveyed,” they ask questions. In particular, every leader must push their group to answer tough questions.

Over time, as a group’s problems and situation change, the answers its members have devised must change as well. And because leaders play a critical role in helping groups ask their hardest questions and seek answers, the need for leadership is eternal.

Those who aspire to leadership face a stern ethical choice: to push their people to seek true answers grounded in reality or to provide the answers their supporters, stockholders, citizens, or employees want to hear, even if they are full of lies and lead to ruin. It is a test that, sadly, many leaders are failing today.