A life devoted to words; The Diary of Virginia Woolf, Vol. 3, 1925-30, edited by Anne Olivier Bell, assisted by Andrew McNeillie. New York: Harcourt Brace Jovanovich. $15.95

The mysterious cause-effect of diary keeping is an everlasting curiosity to those who do not keep diaries. Record of trivia? Memorabilia? Do-not-forget-me? For my autobiography?

The third volume of Virginia Woolf's diary provides no more answers for the inquirer than do other diaries. It springs, presumably, from some need to communicate, from some instinct against loneliness, some purgation. It is also (in her case) indisputable evidence that wordsm were to her the beginning, the growing, the maturation,the justification, the healing, the explicable and inexplicable, the reason for her life.

It is hard to imagine anyone else who is so completely, joyously a writer. When she is melancholy she recovers her spirits if she can put her pen to a piece of paper; when she is ill she knows she is two-thirds recovered when she is putting down words in her diary, in letters, in the shaping of a new book.

The five years covered by this volume are years of comparative affluence. Her position as a writer is established -- though she still wonders if she will be celebrated. She is no longer stricken with the old anxiety over reviews or the response of her friends -- though she does wish they would speak out. She often talks of her happiness; her husband is her anchor. "The immense success of our life is, I think, that our treasure is hid away; or rather is in such common things that nothing can touch it. . . . What can trouble this happiness?" The panic of the past -- and of the future -- is rarely mentioned during these years.

Occasionally she attempts to record and understand a state of mind, a perturbation, an episode that has turned sour, but the attempts are fluttering and elusive. She often ventures toward deeper confessions of doubt, but all the reticences of her education, all the cultural proprieties, allow her to end the ventures with ellipses.

Here is a very kind woman, but "her style gets on tops of her" (she quotes a friend). Her "style" has a great deal to do with when she was born and into what circumstances, and all the adhering values. "How English -- how summery and how upper class -- how pleasant. . . . This has been going on for a thousand years . . . at least, I can remember summers like this -- white fannels and tennis, mothers & tutors & English houses & dinner with moths getting in the candles & ladies asking one to tea all my life -- so pleasant, so without accent." Yet there is the irony and conflict of an England in the throes of change which is also a part of her "style" but left unstressed.

These scribbles and abbreviations, written at odd times of the day, can be seen as footprints leading to her books. In them one sees her brilliance and her limitations. In her nonfiction is a mind working with a sharp clear reasoning, cultivated to follow logic; the space around her, which she has asked for all her life, aerates her thinking. In her novels, her sensibility, her sensitiveness move her into other dimensions. Her metaphors are enchanting: "My melancholy has been broken like a lake by oars." Her diary is filled with the essence of scenes remembered, drifts of talk, expressions of faces. In an acute moment she recognizes that these are hints of her shortcomings as a novelist. "Scenes follow each other, not plots." It is true that all her novels are perceptions, glimpses, illuminations opening out from each other -- nothing arbitrary.

Plots may have been too decisive for this vivid woman who was so intensely alive and yet who kept a death skull perpetually in sight.