Here's a breakdown of the likely origin and evolution:
* Laborers' Workday: In the past, especially before standardized work hours, workers would often stop work when the sun set, signifying the end of their workday. They would literally "call it a day" when their daily work was finished.
* Factory Workers: With the rise of factories, workers would typically work a set number of hours. At the end of their shift, a bell or whistle would sound, signaling the end of their work. Workers would then "call it a day" and go home.
* Metaphorical Extension: Over time, the phrase expanded beyond literal work situations. It began to be used more broadly to indicate the end of any activity or task, whether it be a meeting, a project, or even a whole day.
Interestingly:
* No single definitive origin: While the above explanation is widely accepted, there's no definitive documented source for the exact origin.
* Similar phrases: Other languages also have similar expressions, suggesting a common human experience of ending tasks and moving on.
So, while we may not know the exact origins of "call it a day," it's clear that the idiom has its roots in the everyday lives of working people, reflecting the need to mark the end of a task and transition to something else.