Nonfiction -- briefly; The Life of D. H. Lawrence, by Keith Sagar. New york: Pantheon. $17.95.

Readers familiar with Lawrence will find few revelations in this book, but Sagar succeeds in capturing the spirit of this evangelical author without asking the reader to become a disciple.

This biography illuminates the thought and art of its subject through well-chosen passages from Lawrence's published and unpublished writings and his 5,000 personal letters. The book also contains over 200 photographs (many never before in print).

Without attempting to condemn or to justify, Sagar presents the historical, personal, familial, and social contexts from which Lawrence burst upon the intellectual scene.

Sagar doesn't confuse the difference between the writer's art and life, despite the many suggestions in his published works that they are one and the same.

When Lawrence is quoted here as saying in a letter that travel is "a splendid lesson in disillusion," we see a self-doubt expressed nowhere in the works written for publication. Such small discoveries sparkle throughout this gracefully written biography.