From a patio in the Berkeley Hills, I scanned the horizon, south to north, trying to take in the immensity of the population below me. Thousands of vehicles traversed the Bay Bridge, big jet planes came and went from SFO and OAK, a cargo ship passed beneath the Golden Gate Bridge.

Just out of site, Ocean Beach met the Pacific Ocean, where only days earlier I had completed a five month, self-supported run across America.

The depths of my muscles and joints still ached immensely.

Five months earlier I had set off on foot from Folly Beach, South Carolina with a 12-pound back pack, a five-month time-frame, a modest budget and an open mind. 3657-miles later I crossed the Golden Gate Bridge, tired and gaunt. My open mind had been spilled, emptied, refilled, dried up and rehydrated many times over.

To walk across a place is to observe and participate in a vast, intricate and complex web of infrastructure. It is to experience the history of that place in a very real and personal way. It is to have a better understanding of what that place is. Where that place is. Who that place is. Why that place is.

To walk across a place is to truly know a place.

Following my run, I spent a lot of time on that patio enjoying the stillness while watching the traffic flow along the 580, the 880 and the 24. I traced the BART trains coming and going, fog pouring over the hills and ravens playing above it all. Having experienced a thin thread across this complicated canvas we call the United States, I now felt the desire to experience the immensity of a single pixel on the global map.

To experience a city on this level is, in a way, to experience all cities. There are certain universalities found in clusters of people around the globe. There are places to eat, work and sleep. There are means of moving people around. There are places for entertainment. There are places for contemplation.

But still… why walk? Why run? There is a mantra in the shuffle and a prayer in the suffering. I know what that does for me, but what does that do for you? And everybody else?

The 2500-year-old legend of Pheidippides tells us about a common Athenian soldier who ran from the fennel fields of Marathon to the Acropolis in Athens to announce victory over the Persians. Upon arrival he delivered his message, only to perish from exhaustion moments later.

And perhaps that is why. Because the runner is messenger and his suffering must be witnessed.