My husband fell down last night in the bathroom. More asleep than awake in the 2:00 A.M. dark he landed on the brick floor instead of the bed that he thought was near. The back of his head hit the wall, one elbow banged the sink cabinet, the other struck the floor. In the fall, he bruised his right foot and tailbone, scraped his scalp and elbow raw.

Nothing was broken; nothing concussed but the bathroom wall that caved into a neat three-inch depression where the plasterboard met his head. We washed and bandaged his scratches, wiped red drops from the floor, and went back to bed.

“ I wish I knew what happened," he said.

“ You were asleep. You weren't where you thought you were. You fell.”

“ I guess so.” He slept.

I stared into the dark and wondered if this fall was the beginning of the end.

My husband is seventy years old. I am forty. We have been friends for fourteen years; in love for eleven; married for nine. Despite the three decades that separate us, we fit neatly together. I am expansive, he is reasonable. He reads science, I read biography. We both read cartloads of mysteries. He gave me the New Yorker; I gave him National Public Radio. We love big cities, small towns, and muddy countryside. We both drink vermouth before dinner. My brother in a serious tone calls us the twins.

Our years together have swallowed the space I need to see my husband whole. Instead, I see the light in his cautious blue eyes, the smile that's more of a grin, the way he completes the New York Times Crossword puzzle every Sunday - left to right - top to bottom - in pen. I see, as well, when sorting photos for the family album that my husband looks the picture of his father when his father was no longer young. Yet nowhere in the image do I see an old man who can fall down disoriented in the bathroom in the dark in the middle of the night.

Panic that comes on in the dark drowns you. Listening to the steady tide of his breath last night, I thought, “ He'll die.” I moved my foot to touch his foot in the warmth beneath the sheets, but comfort only crystallized the fear. Would I hear him leave me?

If I woke to stillness -- the thought skittered away, resting on the periphery of my imagination. What would I do, who would I call, when and in what order would I tell his five grown children who finally, tentatively, are our friends? This last undid me. I wanted to shake him awake, keep him awake forever.

“What if he falls again? Tomorrow night maybe or the next?” For isn’t that how it begins? One fall, then another; bruises, then a broken hip. Leaving him asleep, I rose to wander the dark house, testing the loneliness of empty rooms and exorcising fate. Back cold in bed, I moved my right foot to rest its little toe against the little toe of his left. I bargained with the God I doubt.

“ One day,” I offered, “ when I am ready the worst may happen, but not tonight. Not until I’m stronger, wiser, toughened for the blow.”

My husband and I have prepared for death in all the easy efficient ways one does. Wills written; his, and mine as well. For I might go first, flattened on the way to the supermarket. We have agreed not to be kept alive should that flattening, in fact, occur. And we have agreed on cremation with some symbolic tossing to the winds.

“ Wherever you think is the nicest spot,” we say. “ Pick a place, gather the family, say some words, and fling. Just be sure the wind’s not blowing back upon you.”

It’s important to say these things. Good to have them out of the way. They are, however, the easy part. Imagining the difference after death is what’s unmanageable.

I have a friend married to a man twenty-five years her senior, a man who's had a bypass. We talk sometimes, she and I, about each other's plans for later life -- good friends, a bookstore, selling the million dollar article. We confer calmly, controlling the danger in tidy sentences until the future comes too close. Then emotions break, tears well, we stop. We comfort each other with other topics. We never discuss the actual end.

I am a competent women, sure of my ability to withstand most of life’s depredations as well as celebrate its gifts. I can hold a job, balance a checkbook, call the plumber. I know to write down what that I cannot keep in my head -- the principles of sound investment, for example, and a schedule of the car’s oil changes. In the countryside where we live these days, I have learned to till the vegetable garden in the summer, stack wood in autumn, and light the woodstove in winter. I could do these things alone if I had to.

When I was single, I lived alone valuing the space and the luxury of silence. I liked my work, loved my friends, and managed with proficiency everything but my always broken car. Having not married early, I fantasized marrying late, finding true love at fifty. Instead when it knocked me flat at thirty I was astonished and grateful.

I could live alone again. I could order my days once more around friends, relatives, and a job well done. It’s not life alone, but life without him that’s the terror. He is the kindest, brightest, most interesting man I have ever known. He captivates me and makes me laugh. He is, you understand, my best friend.

“ I wonder if there is an afterlife,” I said one recent night as we were cleaning up the dinner dishes. “ Or I wonder if the Buddhists have it right and there’s a place where souls pause before their next assignment. I wonder,” I said rubbing hard at a spot on the counter, “if twenty years from now you’ll be there. Watching me.” Watching over me, I meant.

“ No,” said my husband -- my reasonable, cautious, best friend of a husband. “ I will not be a friendly soul someplace in the afterlife. I will not be watching you. I will be dead.”

Hands on my shoulders, he turned me to face his truth. “ Twenty years from now you will make an even better life than we have now. You will be fine.”

‘Fine’ is his superlative; it means terrific.

He is right. I’ll be terrific. I owe it to myself and to us. My homage to our happiness.

Tonight, however, I will wake up and listen in the dark to the steady tide of his breath. I will move my cold foot to rest against his warm one. And I will remind the God I doubt of our bargain. I am greedy for the years ahead, greedy for every single solitary second. Eleven years have not been enough, neither will twenty suffice.

“ So, not tonight. Remember. One day, but not tonight.”