Twitter CEO Jack Dorsey is a deeply thoughtful man. He loves cities, is passionate about transport, and doesn't want to disrupt existing business models as much as drive revolutions through purpose, values, and leadership.

He's also a man who has started two billion-dollar startups.

Those startups -- Twitter, of course, and Square, the payments company -- have taught him a thing or two about what to look for in employees.

"You don't have to start a company to be an entrepreneur," Dorsey said at Tech Beach Retreat in Jamaica earlier this year. "We place so much emphasis on founding, but there are multiple founding moments in a company. I don't consider entrepreneurship to be a job ... it's an attitude."

That desire to find entrepreneurial candidates reaches deeper than simply finding people who want to create change, though. For Dorsey, it's a question of values, because values drive passion.

And that's critical in employees.

"The one question I ask every single candidate coming for a job is: Why are you here?" Dorsey said. "If you have a sense of passion and a sense of purpose ... then we can work together, then we can build amazing things together."

Dorsey has been building things since his early teens, when he found flaws in a website that enabled him to read a company's internal emails. After he emailed the corporation's chairman, Dorsey was flown out the next week to help fix the problem.

Twitter grew out of a podcasting startup, and Square was born when a friend couldn't buy something from a street vendor who couldn't accept credit cards.

That kind of dedication to fixing things results from the passion and purpose that Dorsey seeks in every new hire.

And it can come from every layer of the organization, according to Dorsey:

"The first thing I said when I came back to the company is that an idea that can change the course of the company can come from anywhere in the company."