It’s a seasonal shift, more dramatic than any autumnal equinox or daylight saving “fall back.” One day the sun rises and the world has transformed into a playground — one covered with fake snow and inflatable Santas, where wire deer bob their lighted heads through the night on the neighbor’s front lawn and icicles glow from the eaves of every home. Suddenly, we’re surrounded by gaily wrapped packages tied with prefabricated bows and the tinny sound of Christmas carols greets us everywhere. Happily we sing along:

Sleigh bells ring are you listening?

In the lane, snow is glistening.

Screech.

It’s not snowing. It’s 70-plus degrees outside. And those bells you hear ringing? Those aren’t sleigh bells. That’s the death knell of Thanksgiving.

It was inevitable. The creep of Christmas toward Thanksgiving has been going on for years, and the holiday of thanks is on the verge of being subsumed completely.

Way back in 1621, the Pilgrims (Puritans) had a good harvest, which was a lucky thing, considering the closest grocery store was an ocean away. So, they feasted on the bounty of the new world, kicking up their buckled shoes in celebration of their good fortune. Thanksgiving was a meal in which the dear Founders celebrated their survival.

Sometime in the Victorian age, the holiday became irreversibly associated with turkey. Later, the NFL put its brand on the fourth Thursday of November.

Now, Black Friday has a stranglehold, for Thanksgiving is rapidly being relegated to merely the meal, before the nap, before the 5 a.m. mad scramble to snatch up as many Christmas pseudo-bargains as possible before the competition does.

Snatching, grabbing, trampling, if necessary.

The insidious takeover of Thanksgiving by Christmas has not happened of its own volition. Rather, it’s a calculated effort to get people out shopping — the earlier, the better. Some bean-counter somewhere likely arrived at the conclusion that the length of the time people feel “in the spirit” is directly proportional to January credit-card statements. Thus, the message became “Spend!” Spend more, spend longer.

Shopping, especially Christmas shopping, is the big, red economic engine of our consumerist society. In theory, there’s not a thing wrong with that.

Except if it means sacrificing Thanksgiving.

There is not much that’s more important than hearth and home, the blessings of food and family. And nothing is so important that we should stop giving thanks for the bounty we have, because we’re too busy fighting for more — even if it is on sale.