It's fascinating to see what happens when an artist decides he can improve upon nature, or tries to redesign her. It cannot be done - unless his idea of ''improvement'' is based upon a profoundly holistic perception of order that takes nature's laws into account, and unless he sets about his task with sensitivity and respect.
Few artists, however, have such vision and tact. Most reduce nature to a series of pretty pictures or to a series of pretty shapes and colors.
''Grant Wood: The Regionalist Vision,'' a major retrospective of that artist's work at the Whitney Museum here, indicates that Grant Wood came close to being such a limited artist. With few exceptions, his work lacks vision and depth, and packages life too neatly and coyly.
I say this with great reluctance. I was raised on Wood's art as a boy in Minnesota and Wisconsin and have retained a very real affection for it. Wood, together with Thomas Hart Benton and John Steuart Curry, were the idols of the new native American art coming into prominence during the early 1930s to counter the ''foreign'' influence of European modernism. Thanks to this trio of painters , the citizens of the United States - and most particularly those of the American Midwest - were finally going to get their very own art. It would be about American farm and small-town life and would be perfectly understandable by everyone.
Grant Wood, in particular, was the hero of the hour. His ''American Gothic'' had put Regionalism on the map, and every Midwesterner over five had heard of him. He was talented; he was famous; but best of all, he was American. I met him once and will never forget it - just as I will never forget that I first saw Curry's ''John Brown'' on his studio easel in Madison, Wis., and actually shook hands with Benton when I was 16.
I remember those days - and that respect for Wood - vividly. And because I do , I looked forward to his Whitney retrospective with both eagerness and apprehension.
My attitude toward his art had altered dramatically over the years. I thought highly of him for having painted ''American Gothic,'' certainly the most famous (as well as one of the best) American pictures of the century. And I liked a few of his landscapes, especially the superb ''Spring Turning,'' and most of his lithographs.
On the whole, however, I recently had found his work dry, static, mannered, and more dictated by formula than by art's deepest imperatives. I felt that when he had succeeded at all - in a handful of paintings and in most of his prints - it was because his sympathetic feelings for some of his subjects had overwhelmed his impulse toward oversimplification, formal rigidity, and coyness.
Even so, ''American Gothic'' could easily have ended up as satire, and ''Spring Turning'' could just as easily have ended up as design or calendar art.
Those were my thoughts as I entered the Whitney. The exhibition does full justice to Wood. It was organized by the Minneapolis Institute of Arts and curated by Wanda Corn. Its roughly 90 paintings, drawings, and prints trace Wood's development from his early Impressionist works done before 1929 through his mature Regionalist paintings and lithographs of 1930-42. Included are most of his famous paintings and more than enough supporting photographic material.
The only problem was Wood himself. Although I had gone, hoping against hope to discover that he was better than I had thought, I came away more convinced than ever that he does not belong in the company of America's few really major painters. And that his social and formal dreams for a truly American art had never had a chance.
This was because his outstanding paintings represent an ending rather than a beginning. ''American Gothic,'' ''Daughters of Revolution,'' ''Arbor Day,'' ''Midnight Ride of Paul Revere,'' ''Parson Weems' Fable,'' and a few others celebrate an America that no longer existed.
Such works as ''Dinner for Threshers'' and ''Farmer's Wife with Chickens'' are idealized icons of a way of life already gone - although it was still fresh in the minds of the older generations. These paintings, and others like them, look backward toward a simpler, rural America - and as such, could hardly have served as the beginnings of a viable and dynamic new American art.
I can attest, having spent my summers from 1936 to 1940 on Midwestern farms, that Wood's accuracy in portraying the appearance of farmers and chickens did not extend to the contexts within which he placed them. Realistic as he may have been in detail, he was, I'm afraid, utterly romantic and nostalgic - even somewhat archaic - when it came to the larger dimensions of his art.
In this respect he was closer in spirit to Norman Rockwell than to any other American painter. Only his interest and concern for certain subjects saved him - but then, to be fair, the same can be said of Rockwell.
I'm sorry to be so rough on Wood, but he's entering our art-history books, and we have to decide if he deserves a paragraph, a page, a chapter, or only a footnote. I personally believe he deserves a page and a half - together with a full-color illustration of ''American Gothic.'' Nothing less will do him justice.
If that seems excessive after what I've just written, let me add that almost all 20th-century American artists have been small in scope, exceedingly narrow, or seriously flawed. In fact, only a few (such as Jasper Johns, Richard Diebenkorn, and Frank Stella) of our living art-world favorites will survive long enough in our memories to be given a major museum retrospective 53 years hence - the length of time between the year ''American Gothic'' was painted and today.
After its closing at the Whitney on Sept. 4, this extremely interesting and valuable exhibition will be at the Minneapolis Institute of Arts (Sept. 25-Jan. 1, 1984), the Chicago Art Institute (Jan. 21-April 15, 1984), and the M. H. de Young Memorial Museum in San Francisco (May 12-Aug. 12, 1984).