UNDERWRITTEN

I want to start with four seconds. If you watched public television anywhere in the United States between 1971 and January of this year, you know these four seconds. A human face in profile, rendered first in the three colors of mid-century corporate design, recast in 1984 as a trio of interlocking faces on a field of white. Six synthesizer notes descending, resolving to a sustained major ninth chord. A voice that said three words. This is PBS. The sequence took less than four seconds. Before it ran: documentaries, children's programming, nature films, dramatic adaptations of novels too difficult for commercial television to attempt. News came after it. Cooking instruction followed. Home-improvement demonstration, classical music, weather announcements on rural affiliates, local public-affairs segments, national programming from Omaha and Boise and Portland and Lincoln, Nebraska, all carrying the same four-second preamble.