LAST Thanksgiving my wife was trying to explain to our granddaughter, Lizzie, 5 at the time, that some of her ancestors had been participants at the original 1621 feast in Plymouth. “I know,” said Lizzie, who apparently had been learning about Thanksgiving in school. “We’re Indians!”

Actually, Lizzie’s forebears were Pilgrims. (My wife, like several million Americans at this point, is a Mayflower descendant.) Nowadays Pilgrims, with their funny, steeple-crowned hats and buckle shoes and their gloomy, pious ways (no games on Sunday, no celebrating even of Christmas!), have gone out of fashion. It’s true that upon arriving in the New World they were so hapless that they would surely have perished during their first winter without the help of the American Indians.

But the Pilgrims were nevertheless heroic in their way. There were a great many Puritans in England at the beginning of the 17th century who wanted to purge Christianity of what they considered the laxity and corruption introduced by Rome and by the insufficiently rigorous Church of England. But only a few hundred of them felt strongly enough to become separatists and emigrate to another land....