Thanksgiving Day is a major
Prayer Book feast, one of two national days (the other, since 1928,
Independence Day) recognized with its own propers [assigned prayers and Bible
readings]. "Agricultural festivals are of great antiquity, and common to many
religions. Among the Jews, the three pilgrimage feasts, Passover, Pentecost,
and Tabernacles, each had agricultural significance. Medieval Christianity also
developed a number of such observances, none of which, however, were
incorporated in the Prayer Book. Our own Thanksgiving Day finds its roots in
observances begun by colonists in Massachusetts and Virginia, a tradition later
taken up and extended to the whole of the new American nation by the action of
the Continental Congress." (Lesser Feasts and Fasts - 1994, p.
438.)