Q. "We have recently learned that my mother, who lives in another state, has a terminal illness. How soon and how much should we tell our 26-month-old son about his grandmother's condition?

"I don't want to burden him with information he can't comprehend, but feel I should prepare him in some way for the inevitable.

A. You're right. A child so young can't understand such an abstract concept as death. Even if he has had a pet die or has seen a dead bird on the sidewalk, he couldn't make the connection.

However, parents who keep bad news from children only confuse them with their mysterious phone calls and sudden hushes. You don't want to dwell on your mother's illness, but your child needs some explanation. Since a young child is sure he's the center of the universe, he'll think he is the cause of whatever gloom is around.

It's time to tell your little boy that his grandmother is sick, and that you're worried about her. You would not only tell him because it's his grandmother, but because your child is your friend. In fact, you probably need to talk with him about it as much for your own relief as for his awareness. Even at 26 months, your son is your confidante. Each day you've shared a little more of yourself, in a hundred small ways. Now something is happening to you that is so enormous you need consolation from him almost more than you need it from anyone else.

And you'll get it. At his age he won't be very concerned about his grandma, but he will be concerned about you and will respond by being a little quieter when you're upset, or by giving some unexpected hugs, which will make you both feel better.

This will be the time to go through the photo albums to show your child the pictures of your own growing up, and at the same time have the chance to reminisce and ease your heart.

You'll also prepare your child by having him draw pictures for his grandma to make her feel better, by taking pictures of him to send her, and by letting him say hello on the phone once a week or take part in a family conversation on tape. Even if your mother gets too ill to respond, your child still will feel involved in the drama and this is as it should be. A child, even at 26 months, has the right to be part of the family's sorrow as well as its joy. In his young way, he will make some sense of the life and death cycle, like a story with a beginning, a middle and an end.

To understand death from a child's point of view, you may want to read How It Feels When a Parent Dies by Jill Krementz (Knopf, $9.95), an excellent book. Your situation is a generation removed -- which means very removed indeed -- but the 18 first-person stories will remind you of the wisdom of involving your child, at least a little bit. These children, between 7 and 16, recall their anguish, embarrassment and shock at their parents' deaths, even though one child was only 3 when it happened.

Children don't think like adults, and young children don't even think like older ones, but everybody has feelings. You're wise to consider them.