Medieval Europe
How a Blind Monk's Bookkeeping Launched the Crusades
A blind monk's arithmetic error in a French monastery in 1095 changed how Christians counted their sins—and accidentally launched the Crusades.
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Download on the App StoreCrusadesMedieval ChristianityFranceMonasticismMathematicsPapal HistoryReligious EconomicsMedieval EuropeFirst CrusadePope Urban IICluny11th Century
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