It was a personal letter. It started off addressing all strangers, but narrowed its focus into a private message to her son. But the final paragraphs seemed to open up a more universal message, a message that ‘life has taught me what is most precious’ which echoed the opening lines, that ‘all mothers [should] know such a love and be heal ed by it’. There was an ambivalence in the letter about keeping her grief secret and sharing it with the world, an ambivalence reflected in the secrecy of writing a private letter and then throwing it out to sea, addressed to all strangers in any port of call anywhere in the world.

Somehow discussing the terrible contents of the letter with my friend seemed to make it more real, and that night I could not sleep, trying to turn my mind away from the grief of the unknown mother. I tried not to dwell on how many sleepless nights she must have suffered. How she must have felt that the very marrow of her soul had turned black. It was the grinding, inescapable misery of her loss that kept me company that night.

Usually I avoid thinking about such an all-consuming loss. Why should I torture myself with imagining my own child dead? Whenever a child goes missing and a school photograph of its bright little face shines out from the front page of the newspaper or the television screen, sympathy for the family is mixed with horror that such crimes could exist. But above all there is the fear that it could be our child. No one can fail to be moved by such stories, but only for a parent would the loss of a child resonate with quite such emotional impact. With stories in the news, you can distance yourself from the victims. The very fact that the death is reported in the media makes it seem more remote and so more bearable. But this letter was a direct cry of such anguish.

The letter had dropped through my front door unadorned by the mystique of its beautiful bottle and without any warning of tragedy or mystery, and its contents had hit me unawares with the full force of their stark message. Sitting comfortably before my keyboard, fresh from the banality of the school run and the everyday administration of family life, I had been dropped into another human being’s tragedy – a death which had transformed this unknown person’s life, and whose words, cast on to the sea, had somehow washed up on my desk.

In the days that followed I too became more protective of my children. I saw them through new eyes and held them closer as they set off for school. I was overwhelmed with sadness for the unknown mother. I grieved that she had no flesh of her flesh for whom she could smooth down an errant lock of hair, or to whom she could give a careless hug. Any parent is familiar with the fear of failing to protect one’s child, of failing to shepherd him or her to maturity. Anyone who has loved knows the fear of loss. At some level the letter represented a universal message; it symbolized the anxiety all mothers feel about their children. And yet it was a very individual tale of tragedy.