A PAINTER OF OUR TIME : ANDREW WYETH: A Secret Life.<i> By Richard Meryman (HarperCollins: 447 pp., $35)</i>

The arrival of a knowledgeable biography about Andrew Wyeth has to be considered a great occasion. For Wyeth is one of the very few artists in our time, their numbers continually dwindling, who have managed to resist the truly relentless pressures to sell out to the latest fashion and have stayed true to their own vision. If he has had to endure his share of rotten tomatoes and dead cats, nevertheless he has proved them all wrong in spectacular fashion. He has continued to paint his bleak, mysterious canvases, charged with a haunting intensity, and he has prevailed. He is rich and famous and, if not happy, well, one does not necessarily look for such a blessing in that direction.

Like Picasso, Wyeth had the great good fortune to grow up in a family in which art was the mother lode, the guiding star, the thing everyone did before breakfast and after dinner, like brushing one’s teeth. His father, N.C. Wyeth, an illustrator and painter with huge appetites and energies, presided over his five children with benevolent omnipotence. All turned out to have a gift for painting and drawing, and two of Andrew Wyeth’s sisters, we are told, were even more talented than he was. N.C. Wyeth may have had his faults, but he left his children to find their own paths artistically, while encouraging and instructing. Because creativity was so much admired, almost taken for granted, it flourished.

One gets the impression of the N.C. Wyeth household as bold and sprawling and more than a little bohemian in tone, littered with children’s toys and kittens and vast tureens of soup and women drifting around half-dressed and the old boy in the turbulent center, splashing paint in all directions. And there is no doubt that N.C. Wyeth was the pivot around which the household swam, although some of the lesser planets were unwilling satellites. Two of his daughters, Henriette and Carolyne, established their independence at an early stage. Andrew, their frail younger brother, remained a daddy’s boy, which we understand from popular writers about psychology can be dangerous for a son’s emotional development. His way of avoiding parental control--so complete, he once said, that N.C. would have arranged his palette for him if he’d had the chance--was to hide his feelings, make jokes that had an unsettling quality about them and “vanish� at crucial moments. That ability to disappear was a trick he refined so completely that he could do it even when he was there. One day a relative arrived at the house unexpectedly to find Andrew’s baby son, screaming upstairs, soaking wet, while he painted on, oblivious.

Art was his means of escaping into a world he could call his own. That truth is stated over and over again in his canvases, which are utterly solitary. When human beings do intrude upon them, their faces are as expressionless as sleepwalkers’. The exquisite and obsessive detail, the steady single-mindedness of the artist’s gaze, which has looked with such intensity that the feeling has been transferred to the painting itself, all of this demonstrates the central truth: his sense of apartness, even impotence.

Photographs are wonderful mirrors, since people seldom defend themselves as completely against the camera’s eye as they do in ordinary life. There is a photograph of Wyeth in an armchair, with his wife, the extroverted Betsy, so gay and at ease with herself, standing beside him. Wyeth’s gaze is wary. His right hand, his painting hand, is crumpled up in his lap as if crippled and his other dangles limply over the edge of the chair arm. There is something sadly stunted about the personality of this remarkable man, which shows itself in relationships and in his fascinated attraction to the same subjects over and over again, those of illness, putrefaction and death.

Richard Meryman, a former editor of Life magazine, has known the artist since he first wrote about him in 1964 and has had to deal with the fact that there is very little outward drama in the story of Wyeth’s life. A talented boy got the encouragement he needed, was an immediate success, could afford not to commercialize his work as his father had been obliged to do, married and had two sons and became famous.

Almost the only drama of his life concerns two models, who may or may not have been mistresses. One was the famous Helga, whom he painted, again always with a blank expression, with the perfection of a miniaturist. He was so secretive, Meryman claims, that his wife did not find out until 65 paintings had been made. This was apparently a great achievement since she came to dominate him as completely as his father had done. Art critics were wrong, Meryman writes, to state that the triangular relationship was a publicity stunt. He claims that it was quite genuine and that the marriage was almost destroyed.

Given the apparent lack of incident, the author’s decision to charge his prose with the same intensity as that of his subject’s inner life is understandable. There are some charming passages and some of Wyeth’s own comments are wonderfully evocative, as when he explains that the Olson house, made famous by his painting “Christina’s World,� is “the doorway of the sea to me, of mussels and clams and sea monsters and whales.� But by focusing so tightly on Wyeth, his family and inner circle, we learn almost too much about the life stories of his brothers, sisters and relatives and not nearly enough about his relationships with the larger world.

This is less a biography than an extended essay, a rumination on life, death, decay and solitude, in language that tries for poetic metaphor but is not always successful. Thus we have such notions as houses that “watch you, their eyes bandaged with blinds,� references to life “ticking� underground and such irritating slang expressions as “a buzz.� These lapses are regrettable since the reader would like to believe that no gulf separates the text from the spare perfection of this artist’s work.