So many parents have done it - or something like it - at some stage, almost without thinking, and yet now, fifteen days after four-year old Madeleine McCann's disappearance, what parent would leave their child asleep in their holiday apartment to have a meal nearby?
The cliche "every parent's nightmare" has been bandied about in connection with this dreadful story precisely because it is so apposite: what has happened to Gerry and Kate McCann, and their other two children, is indeed every parent's nightmare: a family ruptured by an improbable intrusion into their lives, a one-in-a-million chance.
And yet is the lesson from such events that parents must cocoon their children lest harm ever befall them? There is ample evidence to suggest that this doesn't work either; the one-in-a-million chance will happen in any event and those children who are, for the most part needlessly and obsessively protected from the world at large, will be less adept at recognising real dangers, less adept at coping with threats when real need arises.
Right now, no one truly knows what happened to Madeleine and for the McCann family, the agonising wait must go on. Today, they are surrounded by their extended family and friends, by people from Praia da Luz horrified that such a thing could emanate from their community and who desperately want to help and comfort, and by many journalists who, despite the cynical and self-interested motives of some, are very often a source of comfort and support to people in deep distress who nonetheless are the subject of their attention. And the family cannot but be heartened by how their plight has evoked such enormous sympathy back home in Britain and in the wider world. As evidence of this, a website - www.bringmadeleinehome.com - which was set up on Wednesday afternoon had been accessed by some 50 million people by noon yesterday.
But all of this will end, one way or another. The conclusion everyone is praying for is the safe return of Madeleine - unharmed and undamaged by whatever experience has befallen her. Another possible outcome, the unspoken fear in everyone's heart, is the dreaded finding of conclusive evidence that Madeleine will never be coming home.
A third possibility, however, might be even harder for the McCanns to cope with - no conclusion at all. If a decisive end to their torture does not come about one way or the other, that torture will continue, exacerbated by the unceasing imaginings of their own minds, endlessly filling in the gaps, forever painting mental pictures of what might have happened to their little girl.