Settling upon superlatives is a fascinating exercise. Sifting through all the knowledge in the history of the world (well, that's what you'd have to be doing, wouldn't you?) to arrive at a conclusion of momentousness ought to be a fine mental workout.
It would be hard to both be serious, and certain. But that doesn't take away from the value of the exercise; it just hauls one up a few inches short of the goal line of positiveness.
A favorite topic for this cogitation is The Most Important Invention Of All Time. Sometimes I think I may have moved a bit closer to conclusion, but not often. What I do know is that time and again, my default answer is the telephone.
Most inventions are something more on the order of evolutionary. A progression of thinking and improved mechanical technology allows an advancement to come together.It might be argued that the telephone is like that as well, an evolution of the telegraph. But it seems that there's a break- an enormous one- at the actual real-time transmission of a human voice.
It's not hard to picture a clear division in human history at the point telephony became possible. After that point, instantaeous interactive communication became possible, in the method most comfortable and efficient to humans, the spoken word.
At this later remove, it's becoming harder to solidly imagine the lack of the possiblity.Long distance travel is a good illustrator. A person traversing the Atlantic in the 15th century had no grasp of being able to communicate with another person back at home, at least, not beyond simple imagination. It could hardly have occurred to our sailor to be able to discuss something that way, with an active exchange and vocal inflection and instant absorption. The world view that would result from that would certainly have to be far different from ours. A person alive today has every expectation of a capability to converse with practically anyone else on the planet (so it seems), and in very short order.
If nothing else, conciseness would be expected to be an early casualty, eh?
It's hard not to take this a bit further and suggest that the instantaneousness of it all would necessarily breed impatience. I don't know if Joe Average 2007 is more quantifiably impatient that Joe Average 1807, but I can't escape the conclusion that he is.
The next communications step, television (can there be a word for that- say, "televisional"?) is a whole different concept, with a whole different reordering of world-view, and maybe not one that really would increase the impatience quotient.
But then follow along to the Internet...