Ghosts of goldenrod are seen on an Indian summer day. Photo by Dana Wilde

Funny what you remember.

A day in early October, mid-1970s. Sitting alone at a picnic table beside Crystal Lake in Gray, eating a sandwich. Glass-smooth, dark water. Shore fringed in reflections of red, yellow, orange leaves and pines. Air as clear as the lake. No breath of wind. A day so transparently beautiful you can almost see through it to the origins of autumn.

It was barely 70 degrees, but felt hot because the autumn chill had been on for weeks. Days below 60 degrees; 30s and 40s at night. Tree colors in early October were usual then. This, I remember thinking gratefully when I came to my senses at some point, is Indian summer.

Warm, cool, mild. Then chilly, even cold. Then a few brilliant days of warmth. Indian summer in late September had a smokey, gauzy, gold-lit tint. Winter peered out from under north, and then the season of mists and mellow fruitfulness regained its summer face for a spell. It felt like a reprieve.

It did not feel meteorological. The weather scientists, whose job is to nail everything to a definition, state: “True Indian summer is a period of abnormally warm weather following the killing freeze of autumn. A killing freeze occurs when the overnight temperature reaches 28 degrees or colder and may or may not occur with frost. Indian summer typically occurs in mid to late autumn and can occur more than once.”

Where the word “true” comes from here is anybody’s guess. Indian summer has almost nothing do with 28 degrees. It is the interlocking of your inner clocks and sensors with the season.

A Penobscot story gives a much more precise account. A man named Zimo got sick during the harvest and could not bring in his crops. So he asked Glouskap for help. Glouskap told him to go ahead and replant, which Zimo did, and, sure enough, the weather cooperated with a warm spell and Zimo got a late harvest. Since then, the warmth returns every fall, and the Penobscots call it “person’s summer.” Western Abenakis in a similar story call it Nibunalnoba, or “a man’s summer.”

How we of English-speaking descent got the phrase “Indian summer” out of all this perplexes the scholars. It first appeared in writing in the late 1700s. One theory of its origin is that when the original European settlers worried the first frosts signaled the onset of winter, the Natives reassured them spells of warm weather were yet to come. Another theory is that the phrase reflected the time of year the Natives preferred to hunt. A variation suggests it named the time the Natives routinely left their summer digs and headed inland for winter. The hazy air paralleled their campfire smoke.

A more insidious theory is that fearful settlers welcomed the warm spells as harbingers of winter when the Natives supposedly had difficulty mounting attacks on settlements. No historians give credence to this, although it does bring up the tricky, sticky problem of whether the phrase itself isn’t offensive to indigenous people, who for centuries have been deceived, demeaned, demoralized, dispersed and destroyed by white people. The word “Indian,” a mistake from its very first use, is a reminder of catastrophe.

But Indian summer refers not to a bald meteorological phenomenon, and not to dangerous others, but to a sense of an ending.

In the stillness of an October lake, in the breath of a late rose are the grace, serenity, awe, providence, autumnal melancholy and reverence we recognize in the Wabanaki peoples’ generational familiarity with fall. Indian summer has no more fixed time, place and condition than do memories, recent like ours or millennially deep like the Wabanakis’. It arises as it will, and graces your day, then settles back to its right place under the onset of winter.

Henry David Thoreau mentions Indian summer most frequently in October. He watches for it in November, which is when its European counterparts — British All-Hallows summer, French été de la Saint-Martin — usually turn up.

Ever admiring of the Natives, Thoreau writes in his journal at one point: “The future reader of history will associate this generation with the red man in his thoughts, and give it credit for some sympathy with that race. Our history will have some copper tints and reflections, at least, and be read as through an Indian-summer haze.”

We use a phrase in reverence of those indigenous spirits who were the virtues living inside the season.

Indian summer, in other words, is a grace period.

It is disappearing. In recent years, the stretches of chill that used to descend on cosmic schedule here in September, like the one that 45 falls ago turned an October day transparent, have been absent. No winter chill, no summer warmth. Twenty-two of the past 25 Septembers have been warmer than normal, according to meteorologists. As warmer weather invades, as it is inevitably going to do from now on, Indian summer recedes.

The Wabanakis turned out to be tougher than anything white people could do to kill them. That spirit, whatever it is, lived. Toughness is a virtue. So is ancestral memory. Much more powerful even than sitting by a still, calm, crystal lake when you sense but cannot quite see through to the origins.

I hope redemption glimmers somewhere inside a phrase.

Dana Wilde lives in Troy. You can contact him at naturalist1@dwildepress.net. His new book “Winter: Notes and Numina from the Maine Woods” is available from North Country Press. Backyard Naturalist appears the second and fourth Thursdays each month.