At first, it seemed like a crazy idea: change the deeply ingrained habits of millions of people merely by resetting their clocks.

In 1918, when daylight saving time was adopted by the U.S., some Americans didn't even own clocks. On the nation's farms, the sun was the arbiter of time, and you could no more schedule sunrise than you could repeal the laws of gravity. If the idea of turning clocks ahead was to fool people about nature, an opponent of the new time scheme argued, why not reset the freezing point to 45 degrees so people would feel warmer in the winter?

Today, most people are resigned to the semiannual inconvenience of springing ahead and falling back. During the summer, they prefer to shift their extra sunlight to the evening, when they can hit the links after a day's work. But in the early 20th century, the idea of fiddling with the national clock pitted industry against industry and technology against nature.

The father of daylight time was William Willett, an English builder who, in 1907, proposed advancing clocks 20 minutes each Sunday in April and reversing them similarly in September. "While daylight surrounds us," he wrote, "cheerfulness reigns and anxieties press less heavily."

American advocates of daylight saving time, led by Marcus M. Marks, then president of the borough of Manhattan, claimed that people would stay out later on summer evenings, playing games and spending money, which would make everyone healthier and wealthier.