I have a friend who is immune to clickbait. She can stare down the link to a provocative article, ponder its potential significance, stifle her own curiosity, and move on with her day. How does she do this, I have often wondered, and why am I such a sucker?

In his lively new book, Why?: What Makes Us Curious (Simon & Schuster, 272 pp., **½ out of four stars), astrophysicist and best-selling author Mario Livio provides a provocative set of answers, examining the quest for new information through the lens of two remarkable thinkers: Leonardo da Vinci and Richard Feynman.

After a brief rehash of their extraordinary lives — Feynman won the Nobel Prize in Physics in 1965 and was an ardent admirer of da Vinci — our narrator turns his attention to the scientific underpinnings of curiosity. But there’s a problem: curiosity is hard to define. As the author notes, “phenomena as diverse as the drive to conduct deep-ocean exploration and the emotion evoked by watching Jeopardy! on TV are often grouped under the same curiosity umbrella.” How does one explain something so amorphous?

Livio does his best. He tackles the assignment by presenting a mass of conflicting research — experts can’t say whether curiosity is a pleasurable or painful state — before drawing his own conclusions. “Curiosity,” he writes, “may actually encompass a family of intertwined states or mechanisms that are powered by distinct circuits in the brain.” While that vague assessment may be accurate, it’s not particularly satisfying.

Things pick up in the latter half of the book. Here, Livio focuses on the evolving views of curiosity, which was once known as a deadly sin, situated “somewhere between sloth and pride.”

The search for knowledge, he reminds us, has been a dangerous pursuit throughout history. Greek mythology contains many stories of mortal punishment inflicted upon humans who were too curious, and the suppression of curiosity is a common tool to subjugate others. (One might argue that today’s charges of “fake news” represent the latest iteration of this phenomenon.) In some cultures, curiosity is even seen a form of greed to know unnecessary things. We call it morbid curiosity.

Livio goes to great lengths to interview notably curious men and women, but after finishing the book,…