Between Aristotle and Archimedes: Why Were Gears Made Visible Through Rock Crystal in the Late Renaissance?

Out of all Renaissance luxury goods, rock crystal objects and geared devices have undergone the most dramatic shift in value perception since the early modern period. Toothed wheels, once meticulously crafted by skillful masters, are now regarded as the quintessential elements of mechanization and mass production. Rock crystal, once considered a natural marvel whose transparency inspired powerful symbolic associations, has lost its absolute dominion in the realm of transparent materials. The modern public can hardly distinguish between rock crystal artifacts and glass ones, as the semantic meaning of the word ‘crystal’ has shifted from indicating the semi-precious stone to the synthetic silicate glass product developed since the 15th century to imitate the mineral. This paper explores why, between approximately 1550 and 1650 – centuries before the invention of the quartz timekeeper – a combination of rock crystal and gears, the rock crystal clock, became a highly fashionable luxury item among European elites.