From the 1180s, windmills began to appear across the European landscape—devices that harnessed what we now call renewable energy to grind corn into flour but that depended on an impressive degree of mathematical engineering to build.25 New clocks were invented: elaborate devices powered by water or weights that marked the hours without lengthening or shortening them according to the amount of daylight. From the thirteenth century, scholars like the Englishman Roger Bacon began to record recipes for gunpowder—an invention whose arrival in the west would in time come to be associated
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