“Beware of Greeks bearing gifts.” The phrase comes to us from the Roman poet Virgil, whose epic, the Aeneid, recounts the fall of Troy. As the Greeks feigned retreat, leaving behind a colossal wooden horse at the city’s gates, the Trojan priest Laocoön begged his countrymen not to accept it. Whatever this is, he warned, it conceals a threat. The Trojans, exhausted by a decade of siege and eager to...