Perhaps a heightened awareness of the exertion of power has led to Masi's preoccupation with masking, which can be interpreted as the product of an altered perception of personal identity in art. But if actors speak for their author, they are also no more than his puppets. The power struggles on which his work is founded - black and white, God and Man, human and animal, oppressor and victim - are divisions in his own mind. Most potent of these, and the bravest for an artist to considerin public, is the relation between aggressor and sufferer. The elusive bond linking sadist and masochist allows whimsical reverses. Beat your wife for fun and you are liberated role-players celebrating a mutual awareness of the Hegelian master-servant relationship. Beat her in earnestand you end up in jail. "Knowledge is power" wrote Francis Bacon. Yet there is a point where demystification no longer works, where investigation of the roots of aggression shows that we ourselves are the animals, that that "elusive bond" does not exist, that sadist and masochist are equal and opposite, and, which is more daunting, one and the same. For the creative the discovery hurts. Marcel Duchamp called art a habit-forming drug.

Masi's narcotic narcissism, as pervasive in the later work as the earlier, yields one obsessive image, of a creature pressing itself against an impenetrable transparent surface. The activity of rubbing his face over glass which occurs in the series NOSE-WIPE/LIP-SMEAR of 1971 changes slightly in GAME, where a group of rats scurries across a table towards a set of obscure instruments, only to be prevented by a low glass partition. Here, as in GYMNASIUM, piles of splintered glass are included - a token, Masi says, of the "sweetly clean", souvenirs of the swift pain of a cut, invited yet rebuffed by constant, all-over pressure.

In BARRIER the glass shield dividing the table recalls a device used before in MEETING. Screaming in terror, one rhesus monkey pushes it while a companion, uncomprehending perhaps but still sympathetic, shrieks in unison, and a soundtrack evoking pain, division and the limits of the body invites us to extend the range of reference to ourselves. Through the glass the monkeys can see a collection of unique geometric forms - pure, ideal, incomprehensible. The drama is easily described; one of the couple has a sudden sense of who or what it is, of the impossibility of changing. Two animals communicate their mutual fear. And as usual in a Masi "set" there is a powerful suggestion that the staging takes place for the benefit of some unseen human voyeur for whom the viewer is a surrogate; in GAME, SEARCH and MEETING chairs were provided for invisible witnesses. "Identify the barrier. Push the barrier", whispers a voice on the soundtrack. As witnesses our role is to extend the metaphor to personal, existential and socio-political concerns of our own. Yet we have the advantage of dramatic irony. Are those ideal forms what they seem? Emblems of all the monkeys cannot know or make, they are hollow, part of the paraphernalia of trickery, reminiscent of the shell games played by mountebanks to this day.

Drama as a metaphor for Masi's work soon ceases to be useful. Drama requires conflict. Yet this conflict must be capable of resolution in time. In these pieces oppositions are defined, yet no 'end' is possible, nor any emotion comparable to Aristotle's catharsis, that shared discharge of nervous energy produced by Greek tragedy. Instead the atmosphere is thinner, the prospect of common experience more forlorn. ln the last days of the Roman Empire when classical tragedy had sunk to the level of bloody melodrama rich patrons sipped wine as they watched plays in private. Setting and scale were at odds; Senecan drama was overwritten, an orgy of rhetoric and unconvincing horror. Theatricality had assumed such dominance over daily life that sincerity had been ousted by affectation and the significance of acting was itself reduced. Even human sympathy seemed in short supply. Certain works of the 1970's force us to consider such a deficiency in ourselves. In Fassbinder's THE BITTER TEARS OF PETRA VON KANT a grief stricken woman rolls over broken glass, while we remain oddly unmoved. Could it be that Masi's sculpture hurts so much because it exposes our own emotional incapacity? The very impossibility of catharsis leads back to the frenzy of frustration registered earlier in his career, a private lack, infinitely repeatable but never exorcised.

Two experiments show that Masi is prepared to change the terms of his initial response. The first is by implying some transformation akin to magic, whereby he as artist intercedes for the prey, achieves his customary anonymity by ritual identification with his "actors". In HIDDEN SIGN, a six-minute work he called "a presentation gesture", Masi enacted a ritual sacrifice. Before a plinth bearing a patched totem of a seagull he bit through and killed a live eel. An epigraph from Mircea Eliade described the acquisition of a secret language of birds' cries by eating some other reputedly magical animal.