How to Have a Thought: A Walk with Charles Darwin
by Nicholas Day; illus. by Hadley Hooper
Primary, Intermediate    Porter/Holiday    32 pp.
1/26    9780823458509    $19.99

“First you need a rock.” With this statement, Day begins an instruction manual of sorts for contemplation. He takes Charles Darwin as his model thinker, explaining how the naturalist piled stacks of rocks at the beginning of his circular footpath; with each revolution, Darwin knocked a rock off the stack with his walking stick. Walking, Day tells readers, allows the mind to make its way “past the barriers…to the hard thoughts.” Here the book dives into the “hard thoughts” that led to the theory of natural selection, sketching it out briefly but cogently. Hooper uses painting and printmaking to build her illustrations, playing negative and positive space against each other to effectively evoke both Darwin’s era and the rhythms of his walks. One delightful spread depicts the man and his dog on a walk along a looping blue line, Darwin knocking rocks off piles with each loop while the dog gambols with a stick and then stops to scratch; the next superimposes large silhouettes of finches, a giant sloth, and a rhea—all encountered on the HMS Beagle years before—against the green English countryside. Day concludes his exploration by encouraging child readers to “walk your way toward your own hard thoughts,” returning with apt circularity to the story’s beginning. A dense four-page biographical note and a bibliography cap it off.

From the January/February 2026 issue of The Horn Book Magazine.