Woolf's letters: truths, half-truths; The letters of Virginia Woolf, Vol. VI 1936-1941, edited by Nigel Nicholson and Joanne Trautmann. New York: Harcourt Brace Jovanovich. $19.95.

This sixth volume completes the monumental task of editing Virginia Woolf's letters. It is an accomplishment that insures that a remarkable women will be judged as she would like, by her own words.

She wrote often and easily, but not artlessly. One senses that writing to her friends was essential in order to maintain a balance and dimension in her life, which was heavily beset by her own uncertainties. Her wit was often trenchant and at the expense of her friends, but no one seemed to take offense, seeing it, one supposes, as an aspect of her quicksilver mind, which could also be warm and merry and reassuring.

By the late '30s her professional reputation was international. She had undertaken to write the biography of a very dear friend, Roger Fry, and at the same time was struggling with an intractable novel, "The Years." Her letters, however, are only partially the mirror of a writer. She confides what she chooses and no more, and even this is frequently an experiment for her own classification. Many of the letters are truths; many are half-truths, and the half-truths are merely truths dimly seen. On the whole she was writing to artists, writers, poets, musicians -- friends who did not need to have spelled out the vagaries and exhilarations and costs of the creative process.

Her quivers and alarums, when preparing for or working on a new book, are like a shadow play. She needed the drama which she artfully controlled in her letters, though she knew that the truth was much more accessible to her than she pretends. Perhaps she sensed that her friends needed to be participants in a common rite, for she understood the nuances in the art of friendship.

She has remarkably little to say in these letters about the tensions building up in Europe, though her husband, Leonard, as a Jew was well aware of what was happening in Hitler's Germany. When World War II began, her Sussex home was in the path of the bombers attacking London, but she took this with the same spirit of most Britons. Part of this may have been due to her careful balancing of emotions, knowing her vulnerability, her two bouts with madness. Twice earlier in her life she suffered from severe manic-depression, and it was Leonard who helped her to overcome her illness. This perhaps confirms one's sense that her letters, even the most vivid, conceal rather than reveal this remarkable woman.

The war she saw as "a suspension of all reality." Yet she loved courage, she loved the spirit of wracked and bombed London. When she wrote hopeful letters to three friends -- though planning her own suicide -- there was no real discrepancy. The suicide came because she saw no way to escape a third attack of madness which, for her, was a desecration of life and an intolerable burden for the husband.

Her very last letter, to her husband, which he found after her disappearance, is surely the most remarkable, loving and com plete letter she ever wrote.