One of the ways the telegraph changed us as humans was it gave us a new sense of what time it is. It gave us an understanding of simultaneity. It gave us the ability to synchronize clocks from one place to another. It made it possible for the world to have standard time and time zones and then Daylight Savings Time and then after that jetlag. All of that is due to the telegraph because, before that, the time was whatever it was wherever you were.
James Gleick