TO the untutored eye, the differences between Piet Mondrian's ``The Grey Tree'' of 1912 and Jackson Pollock's ``Autumn Rhythm'' of 1950 may seem minimal. To anyone aware of 20th-century art history, however, the differences are major and important. ``The Grey Tree'' represents modernism in its early adolescence, when many of its masters were still groping for formal identity; artistic perfection seemed within reach; and art appeared capable of transforming the world.
``Autumn Rhythm,'' on the other hand, represents modernism at the height of its post-World War II revival, when it had reconciled itself to less than perfection, and had begun to acknowledge that it probably could not save the world.
Both paintings also document important moments in their creators' careers. For Mondrian, 1912 was a year of intense probing and experimentation, of a final break with the past, and of the first tentative hints of what his art would become. ``The Grey Tree'' thus stands roughly halfway between his early, mildly romantic representa-tional landscapes and his starkly simplified geometric abstractions.
For Pollock, 1950 was a year of professional achievement and creative consolidation. After years of struggle, he had finally made it. Not only was he world famous, he was at the height of his powers, with one huge canvas after another - all executed on the floor in his famous ``drip-and-blob'' technique - emerging from his studio. ``Autumn Rhythm,'' one of the largest and best of these, typified his passionate, action-oriented approach to the creation of art.
Both artists rank among 20th-century modernism's dozen or so pivotal masters. Both staked out extreme and uncontestable positions for themselves; Mondrian with his irreducible abstract images consisting of four or five perfectly straight vertical and horizontal lines and two or three unmodulated primary colors, and Pollock with his labyrinthian, totally improvised paintings made by hurling and dribbling paint onto 10- to 20-foot sections of unprimed canvas.
Both were dedicated risk takers, but in very different ways. Whereas Mondrian groped intuitively into the unknown before committing himself, Pollock hurled himself forward with little or no regard for the consequences. Whatever he did, and no matter where he stood in relation to his contemporaries, Mondrian almost always had a well-thought-through ``position paper'' to explain his ideas. Pollock, working completely on impulse and often at breakneck speed, depended on others to speculate on what he had done.
Each, of course, understood fully the importance of such explanations. From the very start, Mondrian and Pollock were derided as charlatans by those unsympathetic to modernism's claims and accomplishments.
Neither one, however, allowed these attacks to deter him. Both stuck to their guns and became highly respected heroes of the avant-garde, as well as militant champions of two of modernism's most extreme and committed forms of nonrepresentational art, Abstraction and Abstract Expressionism.
In ``The Grey Tree,'' we see Mondrian moving from a modified realism to abstraction, from a descriptive analysis of a tree's form and silhouette to a design and pattern-oriented restructuring of its pieces. The trunk and branches interact two-dimensionally (somewhat like leading in stained glass), with segments of sky between.
Mondrian's growth during this period was so rapid that in a matter of months, the tree form all but disappeared, leaving only the near-abstract, allover branch-and-sky patterning that had begun to take shape in ``The Grey Tree.'' This was then further distilled and geometricized until, in 1914, the first of his totally abstract compositions of numerous interlocking rectangular shapes began to appear.
From there, the evolution toward his final style proceeded swiftly and logically. By 1919, everything was in place, and in 1921 he began to produce the work for which he is now so well known.
Pollock evolved even more quickly, if somewhat less systematically. He began as an admirer of the Mexican muralists and, as a student of Thomas Hart Benton, committed himself to modernism in the late 1930s (especially because of the work of Picasso and Mir'o), and by the early 1940s was viewed by those in the know as one of America's most powerful and original younger painters.
The first of the ``drip-and-blob'' paintings came out in 1947 and, in 1950, several of his largest and most impressive canvases appeared in the style that would shortly be labeled Abstract Expressionist. ``Autumn Rhythm'' was one of the best and most ``classical'' of these. It also was to become Pollock's best-known painting by virtue of its continuous display at the Metropolitan Museum after its acquisition in 1957. Not everyone admires it, but for a surprisingly large number of art lovers, it's become one of the highlights of the museum's post-World War II collection.