I've raced on all seven continents at least twice. I've probably run thousands of races. But the single race that I'm most proud is a 10K. Yes, a 10K. I ran it with my daughter on her 10th birthday. Dean Karnazes
The broadest pattern of history - namely, the differences between human societies on different continents - seems to me to be attributable to differences among continental environments, and not to biological differences among peoples themselves. Jared Diamond
Traveling, you realize that differences are lost: each city takes to resembling all cities, places exchange their form, order, distances, a shapeless dust cloud invades the continents. Italo Calvino
Why did human development proceed at such different rates on different continents for the last 13,000 years? Jared Diamond