Bill Gates is one of the most revered—yet most intense—business leaders in history. Gates, along with Paul Allen, founded Microsoft—a company that has had a lasting impact on the software industry, and Big Tech itself. Microsoft now boasts a $3.1 trillion market capitalization.

During his tenure building Microsoft, Gates infamously “didn’t believe in vacations” and worked on weekends. That same level of intensity allegedly bled into the philanthropic foundation he created with his ex-wife, Melinda French Gates, according to an excerpt from Billionaire, Nerd, Savior, King: Bill Gates and His Quest to Shape Our World by Anupreeta Das, published by Business Insider last week. The Gates Foundation launched in 2000, and as of December 2023 holds $75.2 billion in its endowment. French Gates exited the Gates Foundation in May with $12.5 billion in tow.

Working at the Gates Foundation is described as stressful—and staff are terrified of Gates, according to Das, who is a finance editor at the New York Times.

“What comes through about Gates for many is the fear he inspires for a number of things,” Das wrote. A combination of factors “terrifies those who work for him,” Das wrote, from the fact that his foundation operates without shareholders or stakeholders, to his intimidating “brilliance and fame,” to the “arrogant behavior” he exhibited at Microsoft.

Gates Ventures, Gates’ personal office, denies the picture Das paints about the Gates Foundation.

“Relying almost exclusively on second- and thirdhand hearsay and anonymous sources, the book includes highly sensationalized allegations and outright falsehoods that ignore the actual documented facts Mr. Gates’ office provided to the author on numerous occasions,” a spokesperson for Gates Ventures told Fortune.

What it’s like to work at the Gates Foundation

Gates’ meetings with executives and employees from the Gates Foundation, to review plans, budgets, and strategies, were likened to a king holding court—spectacles one former attendee called “almost comical,” according to the book excerpt.

Meetings were “usually held in a big room with a seating pattern,” Das wrote. “Strict etiquette was followed. One former senior executive who participated in many of the meetings said they had the feel of a king holding court, as though Gates were Louis XIV and the employees were courtiers bowing and scraping before him in Versailles, hoping to earn their ruler’s favor.”

Gates Foundation employees would “frantically” prepare presentations for these meetings, “readying themselves for a possible inquisition by Gates.” As detail-oriented as Gates is, these interrogations were inevitable. He would notice even the smallest or slightest deviation from a cohesive story in reports.

“He’s the scariest person in the world to provide a recommendation or briefing to,” one former foundation employee told Das. “He scans a page and comes back at you saying something like, ‘What you say in the footnote on page 9 does not match with the footnote on page 28.’”

But it wasn’t just big presentation days that spurred frenzy at the Gates Foundation. Indeed, “the low hum of fear was a constant presence inside the foundation,” Das wrote. Fear could be instilled from just one email from Gates asking about a grant application or for a task to be done.

“There might be as many as 100 emails among employees—after taking [Gates] off the chain—trying to decipher what he meant, why he meant it, and how they should follow through,” Das wrote.

Still, many Gates Foundation employees proverbially sucked up to Gates, owing to his clout in the tech and philanthropy world. Gates Foundation employees fell into three categories, Das wrote: “consiglieres who bow to Gates; young aspirants who are awed by him; and skeptics who find Gates domineering and eventually leave” the foundation.

The Gates Foundation, in response to a request for comment about work culture at the organization, provided the following to Fortune:

“The Bill & Melinda Gates Foundation has an unparalleled 25-year legacy of working with partners to save and improve millions of lives worldwide,” a Gates Foundation spokesperson said. “With a strong commitment and the guidance of our executive leaders and board of trustees, we are resolute in tackling the most formidable challenges in global health and development.”

The work culture at the Gates Foundation may not be surprising to people familiar with Gates’ habits while running Microsoft.

“I didn’t believe in vacations. I didn’t even believe in weekends,” Gates said in a 2023 graduation speech at Northern Arizona University. “I pushed everyone around me to work very long hours.” He also admitted to overlooking Microsoft’s parking lot each day to “keep track of who is leaving early and who is staying late.”

Still, Gates serves as a prime example of the conundrum executives face: to be loved, or to be feared. While Das’s book draws back the curtain on work culture at the Gates Foundation, Gates believes his behavior isn’t as intense as it once was during his time at Microsoft.

“As I got older—and especially once I became a father—I realized that both in terms of doing your best work and having a great life, that that intensity was not always appropriate,” Gates said in the 2023 graduation speech. “Don’t wait as long as I did to learn this lesson.”