When I turn my key in the lock, the house is still. I enter the living room and, for the first time, everything is in place, almost sterile. Her sneakers are not at the foot of the stairs nor is her sweater tossed on the back of the sofa. No books or papers are scattered on the kitchen table. The telephone no longer rings at all hours with voices squabbling about petty and important things in a language I can't always decipher.

I go to the refrigerator. Once the shelves were laden with vegetables, fruits and milk. Now they are stocked with Dick Gregory's Bahamian Diet, a jar of marinated mussels and a bottle of extra-strength vitamins.

What would it be like, I always wondered, when the last kid went off to college? Would I be lonely or could I adjust to changes like being the sole user of my car instead of a passenger dropped off at the bus stop?

Would I miss yelling at midnight, "Turn down that stereo!" Or would the soundlessness of a quiet house give me the creeps?

How would it be without being shaken awake at 5 a.m. and having questions hurled at me about Jean-Paul Sartre or James Baldwin for an overdue paper? Would being allowed to sleep until 7 a.m. and awakened by the sounds of the birds outside my window be too serene to bear?

Four weeks have passed since our youngest daughter went away to college. Of course, I always knew the day would come and in fact looked forward to it. I saw it as yet another step in her development, one that would ultimately catapult her into womanhood.

I even imagined how it would be when I could take a business trip without first baking a turkey and stocking the shelves with peanut butter or work as late as I wanted to without worrying about her being home alone.

But now that she is gone, I miss her!

Still, I have made some discoveries.

Because most of us working mothers have to juggle so many different roles, much of our nonworking lives is centered on our kids; we dance to the rhythms that our children play. But even after the nest empties, Parkinson's law still holds: "Work expands so as to fill the time available for its completion." What happened to all the time I used to spend going to track meets and PTA sessions?

No, in spite of all the space I theoretically have to fill by not having kids around, there are still not enough hours in the day to do all the things I need to do.

But as the poet Gwendolyn Brooks wrote of times of change in our lives: "Old concepts must be readjusted or restyled, or tested and dismissed -- or rested."

So as I set about readjusting old concepts, I find myself enjoying the removal of "mother constraints" -- enjoying myself as a person rather than always as a parent, and relishing this time when the many obligations of motherhood give way to new freedoms. The freedom not only to choose, explore and know myself better, but also simply to sit and think without having to explain: "No, I am not sick because I'm just sitting here doing absolutely nothing."

I can entertain friends and talk into the morning without worrying about where the kids are, or spontaneously join friends for a game of tennis or a movie without having to hurry home to cook.

Still, I must confess, my relaxed philosophical attitude is partly because my nest isn't empty at all. For the past two months, my oldest daughter has been a new career girl, and still flies in and out of the nest with happy frequency. Then, the many special friends who come and go transform what could be seen as an empty nest if it didn't sometimes feel like Grand Central Station.

And yet another reason for the placidity is that the telephone has become the new umbilical cord. Out of sight is not out of mind because both college girls call to talk of everything -- from the biochemistry examination to the approach of Hurricane Gloria as she unleashed her fury along the Eastern Seaboard.

So I am finding that an empty nest is not the end of the world, but really a new beginning. And if I really get lonely, I can always turn on the "Bill Cosby Show" on Thursday nights and remember, with a relieved sigh, how it used to be.