Browsing through my library collection the other day, I came across Malcolm Gladwell’s 2000 book, The Tipping Point. Back then, Gladwell used an epidemiological model to describe and explain social change. It dawned on me that America is currently experiencing two pandemics--one is disease-related and the other is a people’s movement—and both are being spread by person-to-person contact. The natural and social worlds share characteristics.
