Post Blogger Wharf Rat has been mulling the notion of a wall along the United States border with Mexico. “Down in the pit of my stomach,” he blogs, “the idea of a border fence festers like the remnants of spoiled milk downed with reckless disregard for the carton’s expiration date. In fairness to the Con One, he is not the originator of the idea–just the most recent and most vocal local advocate. Why does this seemingly practical idea not resonate with me? I may have finally wrapped my arms around the reason why, and it all stems from the constraints of recent human population increases…. As the area defended and number of intruders increases, the use of physical barriers becomes much more problematic and certainly less effective.”