The quartet of nonfiction works centers on a common theme, and unsurprisingly, most relate to technological progress shaping civilization during a fourth industrial revolution he helped bring about as cofounder of Microsoft.

“All four are, in one way or another, about making sense of the world around you,” Gates wrote in a post for his blog titled “Books to keep you warm this holiday season.”

Social upheaval in the 1960s

While the list largely relates to technology and its impact on society, he starts off with a personal account by author Doris Kearns Goodwin in her book An Unfinished Love Story.

Gates said he was fascinated by her retelling of the upheaval during the 1960s, all seen through her own eyes as the wife of an aide to both John F. Kennedy and Lyndon Johnson during their respective time in the Oval Office.

“Doris is such a talented writer that the chapters about her love story are just as engaging and enlightening as the chapters about the Kennedy assassination and the Vietnam War,” he wrote.

The link between digital natives and mental illness

Gates goes on to recommend The Anxious Generation by Jonathan Haidt. The Microsoft cofounder called it a “must-read” for anyone interacting daily with today’s youth, whether that’s parents raising their children or teachers instructing pupils. 

This digitally native generation has grown up spending more time consuming TikTok videos or watching Twitch livestreamers, like Kai Cenat, than horsing around in the woods with the next-door neighbors. 

The disintegration of traditional social interaction symbolized by putting smartphones into the hands of children has resulted in surging levels of mental illness and anxiety, according to Gates.  

“Haidt explains how the shift from play-based childhoods to phone-based childhoods is transforming how kids develop and process emotions,” he says. 

Answers to questions you never knew you had

All too often, people pass by marvels of modern society that melt into the background of our industrial landscape, largely going unnoticed. 

Grady Hillhouse’s book Engineering in Plain Sight delves into the various devices that enable our modern lifestyle and how they work.

The author removes the mystery from everyday necessities like cell phone towers and explains in plain English what we would lose if they suddenly stopped working quietly in the background. 

“It’s the kind of read that will reward your curiosity and answer questions you didn’t even know you had,” Gates says.

Risks and opportunities of AI

The Coming Wave explains how artificial intelligence will “reshape every aspect of society,” according to the philanthropist. 

The author is none other than Mustafa Suleyman, cofounder of AI research lab DeepMind, later acquired by Google a decade ago.

After leaving the Silicon Valley giant, he went on to found AI startup Inflection AI, and has been a vocal advocate of the need to regulate artificial intelligence.

“If you want to understand the rise of AI, this is the best book to read,” Gates recommends. (For those readers still hungry, Fortune’s own Jeremy Kahn has followed the industry for years and published his own survival guide for the AI future.)

Gates admits the recurring theme of making sense of the world around us during transformational periods of history wasn’t intentional.

Yet today’s turbulent events mean he wasn’t surprised that he found these four books rewarding to read in the past year.

“It’s natural to try and wrap your head around things during times of rapid change, like we’re living through now,” he said.