Time
Time as an exact concept is fairly recent. In period most people would have been content knowing what month it was and in a lot of cases they wouldn't have minded only knowing which season it was currently. It wasn't until the later parts of period that technology had progressed to the point that mechanical clocks were practical and the first useful pocket watches only started to appear just as the 16th century was drawing to a close.
The introduction of mechanical clocks actually caused much discontent among workers. Previously, they had worked during the daylight hours - when clocks became available, their masters required them to work the same amount of time the year round. Consequently, they had to work more hours, often after the sun had gone down. In some cases, riots ensued.
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