THE SHIFTING FROM SUMMER to autumn has come off with impeccable smoothness. It always does, at least on the calendar. But the change is artificial. The rootholds of summer heat have yet to be dug up by the cool evening or two that have passed through the neighborhood. Summer did not broil the land without entrenching itself in our minds. We are expecting a transition that will be more rough than smooth, and until we get it September is summer.

But even as roses bloom, asters delight and the sun rolls hotly as a ball of fire, nature's movement is forward. Hints of this motion can be seen. Passing over the long fields now are some of the migrant birds, in glides that are practice flights for the trackless journeys about to begin. The berry bushes that feed these travelers are hanging lightly, slowly being picked clean of the proteins needed for the southward haul. A northern haul exists, too. The squirrels manage it. Their hoarding instinct, more obvious than the one of survival but no less sharp, suggests that this is a creature that would rather collect than eat. If there has never been a fat squirrel, as signs say in the health-food stores, then never has there been a still one either. They are at odds with ease.

If it is a time for watching the seasons change, it is a moment also for knowing that all that may be visibly moving is the motion of our eyes trying to see it all. The poets offer counsel, as in Theodore Roethke's poem "What Can I Tell My Bones?":

Weeds turn toward the wind weed-skeletons .

How slowly all things alter .

Existence dares perpetuate a soul,

A wedge of heaven's light, autumnal song .

I hear a beat of birds, the plangent wings

That disappear into a waning moon;

The barest speech of light among the stones.

The hard places of winter are far off, perhaps, but the hints of September tell that the powers of nature are waning. Daylight lessens, animals retreat and growth subsides. A day will come soon when the full shift will be obvious, and we will say now it is autumn and no going back. The delight of autumn is that we won't want to.