When the struggle to save oil-soaked birds and restore blackened beaches left him feeling frustrated and helpless, John Francis decided to take a more fundamental and personal stand--he stopped using all forms of motorized transportation. Soon after embarking on this quest that would span two decades and two continents, the young man took a vow of silence that endured for 17 years. It began as a silent environmental protest, but as a young African-American man, walking across the country in the early 1970s, his idea of "the environment" expanded beyond concern about pollution and loss of...