If you want to prepare for Thanksgiving like a real Pilgrim this year, here's what you should do: Cancel the plane reservations. Stop jotting down recipes. Leave the libations alone.

For the Pilgrims and Puritans, "thanksgiving" days were spontaneous and sober affairs.

When friends arrived from overseas, European Protestants defeated Catholics in battle, or a bumper crop was reaped, the Pilgrims dedicated a day to thanking divine Providence.

They would have considered it presumptuous to schedule a thanksgiving day in advance, said Francis Bremer, an emeritus professor of history at Millersville University in Pennsylvania. "It assumes that God is going to be good to you each particular year."...