It's the rare artist who can point out new possibilities in art. And an even rarer one who can give voice and form to the new through his work. We think of Giotto, who first presented painterly evidence of what was to become the Italian Renaissance, and Masaccio, who pointed the Renaissance toward its greatest heights. We also remember Caravaggio, who paved the way for Rembrandt and Rubens - and Cezanne, who laid the groundwork for much of what we today describe as ''modern.'' And in our own century, we've had a significant number of important artistic innovators and prophets.
But prophetic insights and an influence upon the art of future generations are not all there is to artistic greatness. We must not forget the kind of originality that stands unique in its time and place, and that has very little if any direct influence upon the art of others.
El Greco and Grunewald immediately spring to mind. Their passionately visionary paintings inspired no followers. And the same must be said of the art of Vermeer, Blake, Samuel Palmer, Ensor, and Redon - although the last four did have a few imitators. Van Gogh, Henri Rousseau, Munch, Nolde, Duchamp, and several others also fall into this category. Whatever influence they may have had was largely philosophical and by example; it almost never extended to matters of style. Even Calder, for all his importance and popularity, never had a true disciple.
In a previous age, Calder probably would have had several, and might even have founded a school. But that is not the 20th-century way of doing things. Our suspicion of tradition, and our belief in individual creative expression, make it extremely difficult for a style or formal ideal to be carried forward from one generation to the next.
A few of our more forceful and articulate artists and theorists would like things otherwise. Given a chance, they would have all contemporary art conform to a particular style or ideal. The times, however, do not favor artistic dictatorships; they seem to prefer artistic diversity and individuality.
Individuality can, of course, breed eccentricity, but there is no harm in that. Every age has had its eccentric geniuses, and has been fascinated or amused by them. Without such highly individualistic artists as Bosch, Blake, Ensor, Klee, and Bacon, the world of art would be much less interesting than it is.
We forget that Picasso, the towering figure of 20th-century art, was one of the most idiosyncratic artists who ever lived. We prefer to see him as an innovator and formal ''inventor,'' as the artist who - together with Braque - invented Cubism and then went on to spawn numerous other modernist ideas and forms.
He was, of course, all that, but it wasn't what he set out to be. As he himself once said, Picasso didn't ''seek,'' he ''found.'' Theory, for him, came after the act of creation, not before, and he frequently left the development of ideas to others less inflamed by the creative spirit than he.
Picasso was the great individualist of 20th-century art, the artist who, more than any other, refused to do anything but what his genius dictated. In this he was very ''modern'' and prophetic - much more so, I suspect, than the Constructivists and Minimalists whose basic drives were more toward ritual and conformity.
History will record the direction art takes, and also whether Picasso will be remembered primarily as a great innovator who never quite finished what he started or as a Moses who led the artists of this century toward a promised land of greater individuality.
When that happens, the importance of a number of other highly individualistic artists should be clarified as well. Among the more interesting of these is Richard Lindner (1901-78), a painter of boldly colored and highly fanciful representational canvases that are particularly difficult to categorize. They are related in spirit to Dada and Surrealism, but they also share modernism's fascination with extravagant color and flat patterning. A few are almost abstract, others come close to being brightly colored and delightfully playful cartoons, and some make extremely pointed and acidic social comments.
All, however, are uncompromisingly direct, with images that are sharply delineated and dramatically designed. White figures stand out crisply against dark backgrounds; clothing is garish and exotic; faces are severely stylized; and bodies strike provocative poses.
Lindner's art is intensely private and enigmatic and can be seen as a series of pictorial puzzles to which he alone has the key. But then, that is the nature of this kind of art. It doesn't exist to answer questions but to ask them, and to suggest that reality is more complex and ambiguous than it appears.
Lindner brought great sophistication, a ready wit, and a deep understanding of modernism's accomplishments to the creation of his art. He needed all three, for without them his work would have failed to enchant and to convince, and would have remained too interior and private for general interest.
In ''The Secret,'' for instance, he plays games with geometry, and uses the string held by the boy and the cord held by the girl to form patterns and divisions on the painting's surface. These then interact with the work's other shapes and patterns to create a design of which Leger would have been proud. But that isn't all, for the overall image is richly colored and enigmatic enough to satisfy any Surrealist.
It all adds up to a fascinating work whose effectiveness derives from the tapping of deeply private creative sources, a shrewd utilization of modernist formal devices, and an awareness that art is never more valuable than when it asks questions for which there are no easy answers.