During his headlong, troubled life, the photographer John Vachon recorded an equally restless America weathering depression and war. Although he was an eternal outsider, Vachon had an instinctive feel for every level of society, and his traveling salesmen and fight managers, cops and statesmen, all glow with the burnish of authenticity. In a touching essay, Thomas B. Morgan tells about the man who showed us so much about ourselves.