DICTIONARY JOHNSON is a book long in the making and long looked for by all serious students of its famous subject. After writing his excellent biography of Johnson's invaluable friend Hester Thrale, Professor Clifford traced the early years of her lion-to-be in the authoritative and now standard Young Sam Johnson . That work takes us up to the winter of 1748-49; to the publication of Johnson's greatest poem, The Vanity of Human Wishes , and to preparation for the stage performance of his tragedy, Mahomet and Irene at the Royal Theatre in Drury Lane.

At this point Dictionary Johnson picks up the story of the middle years. Although its author would not see it printed, bound and shelved alongside its fellow, it is heartening to know that he did see the final copy approved for publication, before -- with "no cold gradations of decay" -- his own life suddenly ended.

It is truly startling to realize how enormously in a single lifespan sympathetic interest in the English 18th century has grown, in no slight part thanks to Clifford's innumerable gentle pushes to further its warm acceptance. But, for illustration of the change, take a comparative instance from three representative biographies of Johnson, all favorable, apprearing after World War I. In 1929, Chistopher Hollis published a capital short life, in which he declares of Irene: "I have labored through it, nor is there any more to be said than that it is as bad as a play can be. It was a failure, and deservedly a failure." In 1933, High Kingsmill, a usually perceptive admirer, called the play "simply a versified tract," and dismissed it. In 1944, writing a life at full length, Joseph Wood Krutch says as little as possible about the play, yet specifically this: "Irene was written merely because a tragedy was the first thing likely to occur to an ambitious writer with little knowlegde of the world."

Now, in contrast, Clifford opens with a lively chapter on the literary event of the play's performance, full of comtemporary gossip, expectation, newspaper puffs, first-night audience response, and epistolary reflections. Under Garrick's determined direction, everything was bethought and done to carry things off with eclat . We hear of elaborate scenery, with a Turkish seraglio, an elegant Eastern garden, gorgeous costumes. The best actors appeared in the leading roles: Garrick, Spranger Barry, Mrs. Pritchard, Mrs. Cibber. The audience was fashionable and literate -- and well dressed. For once, Johnson took pains to dress compatibly with the night's importance: a new scarlet waistcoat, gold lace, and a gold-laced hat.

The play provoked mixed reactions, reaching to both extremes. Clifford gives us samples of critical comment, in newspapers and private letters social and literary, from first-nighters and early readers. Good judges praised it, and it more than paid its way. It is noteworthy that nothing of Clifford's well-woven recovery of the occasion is invented. Al the details are based on evidence cited meticulously in the notes. This painstaking accuracy is typical throughout the book and sets it well above the biographical cream-skimmers that spring up like mushrooms, as easy to forget as they are to read.

With the same faithful attention to fact, Clifford devotes his second chapter to exploring what it was actually like to be living in Johnson's house, 17 Gough Square, London, in the mid-century years when he was writing the Dictionary . It is described room by room, from top to bottom, not as it now stands as a public spectacle, but as a domicile. No running water, no bath room. Fires to be kept in each fireplace. Ashes to be removed; dirty water to be carried out. All this, doubtless, was fairly typical of life for the middle class, if not for the well-to-do. The routine inconveniences of one generation can appear insuffarable to a later one.

In Johnson's particular case, Clifford had a difficult counterpoint to orchestrate. His main business is to show how toilsome and drab daily existance in staitened circumstances was for this man, even less comfortable after the death of his comfortless wife, Tetty. He registered the completion of his superb achievement in the Dictionary in these unforgettable words: "Not in the soft obscurities of retirement, or under the shelter of academick bowers, but amidst inconveniences and distraction, in sickness and in sorrow . . . in this gloom of solitude . . . I have protracted my work till most of those whom I wished to please have sunk into the grave, and success and miscarriage are empty sounds."

It is not Clifford's present business to celebrate the succession of shining achievements during these painful years, but to show the life as it is lived. By this time, in our half-century, the critical analysis of each of the major works, and even the lesser, is matter for at least a monograph, often of book-length. Clifford's humbler endeavor is to demonstrate what it was to produce them in self-doubt and desperate depression and actual want. Johnson was close to mental shipwreck in the years before the pension put him beyond the fear of penury and the debtor's prison. In these years he could write to his friend Baretti: "One week and one year are very like another . . . I have risen and lain down, talked and mused . . . I have not, since the day of our separation, suffered or done any thing considerable . . . I have hitherto lived without the concurrence of my own judgement."

As we know, he was saved eventually by moral fortitude, and by his capacity for humane interchange. He became a magnet with power to draw to himself a company so varied and distinguished that 200 years later we are still astonished at its brilliance and fascinated by its intellectual dynamic. But Clifford, knowing that the ground of the last two decades of Johnson's life has been well tilled and cultivated where it becomes highly visible, sets the terminal point of his study modestly with the entrance of Boswell on the scene, in 1763, a year before the founding of The Club, and two years before Johnson's domestic resurrection by the ministrations of the Thrales.

In store for him in the future were his great edition of Shakespeare, and the quite unforeseen Lives of the Poets . Clifford has brought us to where, although for Johnson there was a dreary samesness in the prospect -- "the tired waves, vainly breaking, Seem here no painful inch to gain" -- we can forecast for him almost a quarter century of triumphant life.