Habits are pesky things. They dig in and find a place in your internal machinery, comforting and predictable in a chaotic world. I liked that 11 a.m. ritual. And I'll miss it.

Roy and his wife, Jo, moved on one of those fall days when the sun wasn't certain whether to shine. That uncertainty seemed a potent symbol. They stopped in for a last chat, a last hug, and some promises about staying in touch. Ironically, it was one of the few times they'd ever been inside our house.

We were perfect neighbors, at least by our mutual definition: We liked one another, enjoyed chatting about the state of the world, depended on one another when something was amiss, but essentially left one another alone.

In the six years we shared a side lawn and had decks within sight of one another, we marked some life passages. There were small triumphs, some losses, and mostly a steady, daily, comfortable neighborliness.

On the day a storm felled a tree in our yard, it was Roy who phoned to gently suggest that we might want to check it out. We hadn't even seen the poor fallen evergreen, and he was as careful as a loving parent in breaking the news.

The fact that Jo had made most of the curtains in her house did not make us kindred spirits. The fact that she loved neighborhood yard sales as much as I did was, however, a powerful bond. Early Saturday mornings, we sometimes scurried at the same moment to our next-door driveways, eager to be on with the hunt.

Neighbors are in that odd category: not exactly friends, not relatives, seldom colleagues, yet essential in our lives. Good ones sweeten life. Lousy ones - well, anyone who's ever been in pitched battle over loud parties, barking dogs, and ignored boundaries knows how to finish that sentence.

In the six years since we said goodbye to dear neighbors on a different street and hello to a new set of daily life-sharers, our domestic landscape has changed.

Wonderful neighbors who lived on the other side picked up two years ago and moved back to the city. Their imprint on our lives was short but pleasant. And they left behind the wonderful garden that Eileen had planted, but that we can enjoy still. I miss the sight of her puttering in that garden, oblivious to all but her perennials, a portrait of devotion.

Three houses away, a family with children has arrived - a novelty in this mostly empty-nester territory. I love to watch the boys, who look to be about 12 and 16, toss a ball around in the open space near our homes. I smile and wave to these new kids on the block, even though I don't know their names.

There are rhythms in neighborhoods - those of us who are at home during the day often go out to our curbside mailboxes at the same time. There may be just a nod, or occasionally a conversation about lawns, politics, people or movies. Nothing earth-shattering, but the kind of talk we neighbors exchange to remind ourselves that we are, after all, linked in this space.

I miss the strangest things now that Jo and Roy are gone. On soft summer nights, or even on chilly autumn ones, I would sometimes see them sitting together on the ornamental bench on their front porch, near the red geraniums that always looked perfect. Married 50 years, they still sat close and seemed happiest that way. It made me smile, and gave me hope for enduring pairings.

Looking at that empty porch now makes my heart lurch a little.

On the day of their move, as their worldly goods were being carted out to a behemoth of a moving truck, I heard one of the movers whistling. It was a melancholy tune I didn't recognize, but I couldn't help wondering if he, too, felt that odd blur of endings and beginnings. The last thing to go was their lovely patio table and umbrella . . . off to a new patio 10 miles away in a seniors community.

So now, we are awaiting new neighbors - lucky Jo and Roy sold their house quickly, even in this daunting market. I admit it, I peek out when I hear some noise nearby, wondering whether they - whoever "they" are - have arrived.

Sooner or later, they will. And we will probably exchange pleasantries at first, formal with the newness of our cheek-by-jowl lawns. We'll come to know one another better, I hope, as we weave a new pattern of proximity.

The cycle goes on. Neighbors come and go.

But for now, 11 a.m. feels strangely empty.