FARLEY MOWAT's My Father's Son (Key Porter, 352 pages, $29.95 cloth) has no right being as good as it is. After all, it concerns two extremely well-covered subjects: the author and the Second World War.

Mowat, one of Canada's ablest self-promoters, has put at least some of himself into all of his many books (and much of himself into some of them). And the Second World War is not a historical event that has gone undocumented. Is there really anything interesting left to team about either of these subjects?

As it turns out, there certainly is. Even though My Father's Son covers much of the same territory -- geographical, psychological, and spiritual -- traversed so deftly in Mowat's earlier And No Birds Sang, this is a welcome and surprisingly insightful journey of literary and historical discovery.

Where And No Birds Sang was a passionate look back at Mowat's wartime experiences in Italy, this is an unvarnished, unblinking view of the events at the time, seen through the letters exchanged between the author and his father. Because the writer is Mowat, we willingly put up with the banal tone of the early letters; for our patience, we are grandly rewarded as we gradually become literary voyeurs of the moving relationship between father and son. (There are a few letters to and from Mowat's mother, but the special bond between father and son dominates the book.)

Mowat provides some connecting narrative, and a helpful epilogue, but it is the raw feelings, the forced bravado, hopes, and heartbreaks of a young soldier that shine through. As Mowat proclaims in his preface, "This book is about coming of age in a world gone mad." As such, My Father's Son merits comparison with reflections on the same theme by such writers as Norman Mailer, Joseph Heller, and Kurt Vonnegut.

These letters will appeal to anyone who lived through the war but, more important, they also give those of us who came after a touching insight into the lives of young people thrown into a "world gone mad."