Rest Days is a wide-ranging scholarly study of sacred rest, taboo, and the origins of the Sabbath. Hutton Webster traces days of abstinence not to fully formed religious institutions, but to older customs of danger, purity, and communal restraint found in "savage" and barbarian societies across the world. Drawing on a comparative method, he shows how tabooed days governed behavior, silence, travel, food, work, and even light, often under the threat of spirits, demons, or ancestral powers. From Polynesia, New Guinea, Borneo, and Africa to Babylon, Greece, Rome, and East Asia, Webster follows rest days through temple consecrations, New Year rites, funerary observances, market cycles, lunar festivals, and the rise of the seven-day week. He gives special attention to Babylonian "evil days," lunar taboos, and the Hebrew Sabbath, arguing that Sabbath rest likely grew from older lunar customs rather than from Creation, the Exodus, or Saturn worship. The book closes by showing how holy days, unlucky days, and inherited ritual fears shaped religion, social order, and economic life across civilizations. This edition has been fully restored with modern typesetting, custom cover design.