One animal left India in 1515, caged in the hold of a Portuguese ship, and sailed around Africa to Lisbon--the first of its species to see Europe for more than a thousand years. The other crossed the Atlantic from South America to Madrid in 1789, its huge fossilized bones packed in crates, its species unknown. How did Europeans three centuries apart respond to these two mysterious beasts--a rhinoceros, known only from ancient texts, and a nameless monster? As Juan Pimentel explains, the reactions reflect deep intellectual changes but also the enduring power of image and imagination to...