Can a man have a love affair with a foreign land? Ron Butler never dreamed Mexico would capture his heart and his soul. But when his ex-wife moved to Guadalajara with their children in the wake of divorce, he found himself crisscrossing the country, seduced by its charms and moved by its rhythms and its melodies.

Like the diver of an old Mexican legend who lives beneath the sea seeking the best pearl, Butler lost himself in Mexico and found the hidden treasures of every tiny hamlet and big metropolis. He writes about the endangered monarch butterflies of El Rosario, the...