The measurement of time is a crucial development in human history. From the earliest civilisations, scholars looked for ways to record the movements of the stars and from them compile what can be considered the first calendars. About 2,400 BC, the Mesopotamians imagined a single unit of measure with which to calculate distance and time. It became the basis for the sexagesimal system that still governs how we divide and tell time in units of 60.
The Egyptians, Greeks, Romans and Arabs, in turn, built up an understanding of astronomy that gave rise to sun clocks, water clocks and fire clocks, to the first gear-driven mechanisms, to astrolabes and the universal calendar that we use today.
China was no stranger to this progress. In 14 BC, there were 365¼ days in the Chinese solar year, and the division of time had 60 as its base. The imperial system was rooted in astronomy, and eclipses were carefully recorded from as early as 720 BC.
But it was in Europe that the modern concept of time measurement took shape, from the late 13th century. Nature's cycles gave way to linear time, counted by the huge mechanical clocks in monasteries and public buildings. The transition from clock to watch would take several more centuries.
The first mechanical clock to come to China from the West was sent from Lisbon in 1582 to the governor of Macau. As international trade developed, China became a foremost destination for Swiss watches.
In the 19th century, Swiss manufacturers did brisk trade in "Chinese" pocket watches - affordable, quality timepieces suited to the humidity of the Asian climate and sold in pairs in accordance with the principle of yin and yang.