(See Note Below)
In the mid 1800s telegraph came along. This added a new dimension to sharing ideas. Telegraph is much faster than word of mouth books and publications.
Note: With all that's being said here, time actually ends up as a very simple concept: For time to exist, you only need some combination of 2 or more independent units of mass and or energy in motion relative to each other and you need an observer. That's it, that;s all there is to it.
The so called "Grandfather Paradox" does not exist. If you could build a time machine, go back to a point in time before you were born and kill your grandfather eliminating the possibility of you being born is misleading, the fact that you're here to build the time machine proves that under any circumstances, you failed.