Our understanding of history tends to be spotty at best. There are important dates that we commit to memory (1492, 1812, 9/11) and there is a rough linear sense of when important discoveries were made, events took place, great people died or were born.
But what most of us don't entirely grasp is the larger context in which these moments played out. Unless you dive deeper into a specific period of time — I am a 50's/60's culture buff, but can only claim to have scratched the surface — the individual dates and facts remain isolated; still significant, sure, but in surveying the bigger story that was playing out at the time, there is even greater understanding as to how a theory was derived or why a revolution took flight.
Tim Urban has posted an article over at Why But Wait on his notion of Horizontal History. Basically, the idea is that by plotting "Really Famous People's Lifespans" horizontally through the decades, we are able to note those who were living at the same time (Queen Victoria, Van Gogh, Sitting Bull) as well as whose influence was waning as someone else began to shine (Babe Ruth, Bruce Lee).
From this, one gains a sense of both zeitgeist and continuity. And one becomes acutely aware of the juxtaposition of the brief and finite nature of life against the great, ever-flowing rush of existence.