The year is 1838. The scene is the dense Honduran forest along the Copán River. Two men, John Lloyd Stephens and Frederick Catherwood, are about to rediscover Mayan civilization. Their guide, slashing through the rampant growth with his machete, leads them to a stone column, fourteen feet high, sculptured on the front with a portrait of a man, “solemn, stern and well fitted to excite terror,” covered on the sides with hieroglyphics, and with workmanship “equal to the finest monuments of the Egyptians.” Stephens records their discoveries and also his travels in Central America, while...