Because there, in the hollow between the floor joists, lay a flat tin box, and on top of it, a photograph in a cracked frame.
I lifted them out with careful hands. The board had been fitted to lift and return, by someone who meant to come back to what he had hidden.
The photograph was of a young man in uniform, smiling, forever young. The old man who died alone in this house before us, I would learn, had been his father.
Inside the tin was money. Savings bonds, a thick stack of them, bought one at a time over many years. And a letter.
He wrote that his only son had gone to war and never come home, and that he had kept buying these bonds for the grandchildren that son would now never give him, and that since no child of his blood would ever run through these rooms, he was leaving them for whoever did, for whatever family would one day raise their children in this house.
I sat down on the top of the stairs and I could not breathe for a moment.
Because that family was mine. I had raised four children in this house. I had walked that very hallway in the dark a hundred nights to check on them, sick with fever, and all the while, a foot beneath my feet, an old man had been keeping a gift for exactly the children I was raising.
He had lost his son. He had no grandchildren. So he hid his hope in the floor and left it for the next family to be blessed with what he was denied.
The county found no kin, just as none had come when the estate sold us the house cheap in 1985. The bonds were mine, matured now into a sum that made the teller go quiet, more than that grieving father could ever have dreamed they would grow to.
But they were never really meant for me. They were meant for children raised in this house, and I raised them, and now I have given every bond to my own children and grandchildren, and I have told them the whole story, so they know their good fortune came from a grieving father who kept faith with a future he would never see.
His son photograph I did not keep. I gave it, with the story, to the local veterans hall, so a young man who died for his country would be remembered by more than a stranger who found him under the floor.
Thirty-nine years I walked that floor and never knew a father hope lay beneath it. It found its family in the end. It found mine.