It can be tempting to believe that change-makers whose work affects generations must be extraordinary prodigies; that each one has a remarkable "a-ha" moment when a brainstorm is suddenly transmuted into a single, brilliant idea, obvious in its genius.
"Movies and pop culture get this all wrong: The idea of a single eureka moment is a dangerous lie," says the billionaire entrepreneur, speaking at the Harvard Commencement speech last week.
"It makes us feel inadequate since we haven't had ours. It prevents people with seeds of good ideas from getting started."
Zuckerberg famously launched Facebook while he was a student at Harvard. At the time, he didn't have any understanding of what he was building or how big it would grow.
"I remember the night I launched Facebook from my little dorm," remembers Zuckerberg. "I remember telling [a friend] I was excited to connect the Harvard community, but one day someone would connect the whole world.
"The thing is, it never even occurred to me that someone might be us," he says. "We were just college kids. We didn't know anything about that. There were all these big technology companies with resources. I just assumed one of them would do it."
"If I had to understand everything about connecting people before I began, I never would have started Facebook," he says.
Zuckerberg's speech also makes the case that finding your own purpose is not enough; that young ambitious people ought to strive to take on projects so large that they give other people purpose, too.
Zuckerberg points to putting a man on the moon, immunizing children against polio or building the Hoover dam as examples from previous generations.
"Now it's our turn to do great things. I know, you're probably thinking: I don't know how to build a dam, or get a million people involved in anything," says Zuckerberg.
"But let me tell you a secret: no one does when they begin. Ideas don't come out fully formed. They only become clear as you work on them. You just have to get started."
Building large movements takes time, the confidence to move forward even when the path forward is not clear and, finally, a willingness to be called crazy, says Zuckerberg.
"It's good to be idealistic. But be prepared to be misunderstood," he says. "Anyone working on a big vision will get called crazy, even if you end up right. Anyone working on a complex problem will get blamed for not fully understanding the challenge, even though it's impossible to know everything upfront. Anyone taking initiative will get criticized for moving too fast, because there's always someone who wants to slow you down."
But Zuckerberg's perspective — and the one he is suggesting young graduates adopt — is that there is more to be won by chasing opportunity than there is to be lost by avoiding making mistakes.
"In our society, we often don't do big things because we're so afraid of making mistakes that we ignore all the things wrong today if we do nothing. The reality is, anything we do will have issues in the future. But that can't keep us from starting."