There are no moments more painful for a parent than those in which you contemplate your child's perfect innocence of some imminent pain, misfortune, or sorrow. That innocence (like every kind of innocence children have) is rooted in their trust of you, one that you will shortly be obliged to betray; whether it is fair or not, whether you can help it or not, you are always the ultimate guarantor or destroyer of that innocence.