IN THE FIRST section of this admirable book, British novelist Christopher Leach recounts for his younger son, Martin, the unexpected death in the night from asthma of his 11-year-old elder son, Jonathan. Perhaps because of the awful quiet in Leach's narrative voice, it is the saddest half-hour's reading I have ever spent. My shirt was actually wet from weeping.

It's hard to know whether to urge such a book upon others. I can tell you that Leach is never maudlin, and never manipulative. And after, say, 15 minutes of boo-hooing, it became clear that I was no longer crying for poor Jonathan, nor even for Leach, but for myself, and for my own dead. It was just the sort of catharsis Greek drama never triggered in me, although the deaths of Socrates and of Odysseus' trusty dog, Argos, came close.

For those who are confident in the belief that Jonathan lives now in a better world, the rest of Letter to a Younger Son may seem unnecessary. Leach meditates, without the comfort of religion, on the meaning (or meaninglessness) of his son's death, and of death in general. He does not lightly dismiss the question of faith in a personal God. He believes that there is a force in the universe, but that it is unknowable, and that religion-- that is, man's attempt to explain what he cannot know --is feeble and implausible. "I find it easier to understand this world without a God," he writes, "than to accept it with one. That which has been created seems to me, at times, more noble than its creator." And later he tells Martin, "If the universe is a caring one, it cares less than the consciousness it has created. Or differently. It shows no sign of grief. Shares nothing with me."

What follows in Leach's argument is less bleak. It seems to me to be his most interesting notion: "You and I, as the personalization of that force, have the power to invest that creation with the one aspect it lacks: a desire to hold and examine; to contemplate what it has made, rather than to hurry on; perhaps even to love. Are we the outriders, the scouts of a journey toward love? Are we the first fragments of caring, hung like fireflies in the dark?"

This is a wonderful image, I think, and an exciting thought: that the universe is in spiritual evolution, that we are the forerunners of a more perfect creation, and that the spark of consciousness which so bitterly alienates us ennobles all that from which we are alienated. Finally it doesn't make much difference to us individually, of course, since we are not likely to be around for whatever marvelous thing the world becomes. Leach never claims that it should matter. In the middle of spinning his most shining webs he will pull himself up and say, "But my son is ash," and it all comes sadly unspun.

It seemed odd at first that Leach goes through his paces without relying on the ideas of others, neither philosopher nor poet, especially since he is himself a literary man (one of his novels, The Send Off, won a PEN International award), and all the references he might have made were undoubtedly importuning him. Perhaps he fought them off because he was minding his most important audience, Martin, who at age 10 may yet believe his father to be worth listening to, or may believe, at least, that he is less dull than Plato or Shakespeare, or whomever Leach might have borrowed from. Leach's frame of reference, then, is largely the world observable from the windows of their rural Cheshire home:

"From within a sea of barley I hear a cry. Treading the sea, I discover a hare with a broken back. There has been shooting this morning. Even in these last seconds it knows its enemy, and tries to twitch away. I kill it with a stone. The next day it has gone, pulled somewhere. And then the barley itself goes."

Leach also wished to see whether he, an artist, could create something of worth--for Martin, for himself, for us--out of something so full of pain and empty of meaning as Jonathan's death. He doesn't put it quite this baldly, but it is evident in one of the few references he makes to his wife (or to Martin) that she disapproves of his working while their grief is so fresh. The book is finished within a year of Jonathan's death.

If there seems something hubristic in all this, Leach is at least aware of the difficulty of his task, and aware that the results will necessarily be fragmentary. And he never forgets how puny his efforts are compared with the monstrous mystery and finality of Jonathan's death. But he writes this book because it is all he can do. Jonathan's mother planted a tree in her son's memory. And for Leach: "as a believer turns to the cross, I turn to those sturdy, time-polished counters--English words." Both are acts of faith.

A British reviewer suggested that Letter to a Younger Son might be of use to others who grieve, but I don't see how they could stand to add Leach's pain to their own. It can't hurt the rest of us to be reminded of Leach's conclusions--that death makes life more precious, that we must live fully in what time we have. These are truisms, but Leach makes us feel afresh the truth of them.