from the text Vocabulary Fill: milestone, quest, rotation, leap, context. 1 Astronomers began their www.for knowledge millennia ago. 2 The invention of mechanical clocks was a massive ......... forward. 3 To understand the importance of the merkhet, you need to look at the broader historical 4 The sundial was the first major ........ in timekeeping. 5 The daytime and nighttime cycle is a result of the Earth's​