The religious imagination of the Greeks, Robert Garland observes, was populated by divine beings whose goodwill could not be counted upon, and worshipers faced a heavy burden of choice among innumerable deities to whom they might offer their devotion. These deities--and Athenian polytheism itself--remained in constant flux as cults successively came into favor and waned. Examining the means through which the Athenians established and marketed cults,...