When steel floats

Anthony Caro's sculpture has always refused either to be, or look, sedentary. Even his earliest clay figures were the opposite of ''reclining'' - they were ''waking up,'' lifting away from the ground. His abstract sculptures, and by now there are a large number of them, have likewise stood with great inventiveness in energetic visual defiance of their own center of gravity.

Much of his work's extraordinary freshness and originality stems from this intrinsic - though not too simply obvious - characteristic. It has been called an escape from ''monumentality,'' and in his avoidance of the pedestal, of the single columnar support, of the visible or implied pivot, his sculpture has been freed to explore kinds of movement (and also lightness) that were unseen in previous sculpture.

The term ''monumental'' carries subsidiary meanings of ''impressive,'' ''lasting,'' even ''massive,'' and sculpture has almost always been concerned with that kind of consequence. Vitality struggles to emerge from the marble in a Michelangelo but is ultimately imprisoned by the stone's grand torpor. Even in that most pictorial and mouvemente of sculptors, Bernini, the thrilling moment tends to freeze: Apollo is captured in his running, Daphne is rooted to the spot. It is as if sculpture, by ''remaking'' the human figure in materials more durable than flesh, were bound to be an attempt to ''immortalize.'' In fact, even today, this remains the popular and solemn function of statuary - a function that has often been the very thing to deprive even the most advanced sculpture of vitality.

In terms of Caro's work, it seems that the liberation from this conventional monumentality has, however, also involved the abandonment of certain qualities that he has recently felt might still be productive if they could be introduced without, in turn, overwhelming the essential freedom of his sculpture. It is interesting to observe that at least one writer has found aspects of some of his newest sculpture to be ''heroic'' - scarcely an epithet one would have expected Caro sculpture to prompt.

The series of large steel sculptures in which he has used such heavy units (from a marine dockyard) as bollards, chain links, and giant buoys are the pieces in question. ''Double Variation'' (1983-84) is one of them.

These splendid sculptures are certainly large, though not a great deal taller than a rather tall man. The steel elements in them are weighty in appearance (and in fact). But if the word ''heroic'' somehow suggests a display of muscle, of warrior qualities, of awesome monumentality, then it is definitely the wrong word. The great rounded volume of the halved buoys which are the sculptures' most distinctive feature is not permitted the kind of swallowing dominance it could easily have had. Its cavernous internality is made, if anything, less powerful (and more purely visual) by its role in contrast with, and even slotted behind, the sheet elements. In other words, Caro has contrived to bring a deep volume into his steel sculpture that previously he would have avoided, but he has not, at the same time, let it become a conventional - and sedentary - kind of sculptural ''mass.''

The viewer's eye moves into the sculpture's spaces, and enjoys a new (for Caro) kind of form and warmth - a kind of wholeness, even - but it is no more sculpture that the viewer wants to feel or touch than Caro's has ever been.

It is perhaps coincidental, but the fact that these marine buoys were originally intended to float might carry an interesting connotation in terms of Caro's art. One would logically expect him to find a source of ideas in the ocean - in a surface or ''ground'' always in movement - and in such active states as buoyancy and floating. Also, in a way, the volumes in these recent large sculptures are not unlike those of giant waves. They are volumes opened by motion, by dynamic forces.

These sculptures are a particularly logical stage in Caro's development and exploration of a sculpture that has always, above all, been a thing of ''potential energy.''

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