I started wondering about the role of shyness in the sculptures earlier this year during a face-to-face encounter with Ron Mueck. Not with the man himself, but with the astonishing sculpture he made of his own head in 2002. Drawn in from across the gallery by the sight of this colossal, lone, sleeping face, I could see the pull of gravity on his cheeks, glimpse the shine of saliva inside his mouth, and trace-whisker by fastidiously implanted whisker – the swarm of stubble on his chin. If I came close enough, I felt sure I might hear the whistle of breath through the lips. Here, it seemed, was an example of self-portraiture at its most extreme-a sculpture that tells us everything there is to know about this person and then some; an act of complete and unflinching self-exposure.

Yet the more time I spent with the work, the less certain I felt about what exactly was being exposed. After all, whatever Mueck is thinking or feeling in this sculpture is hidden behind those closed eyes. And the sense of concealment is heightened by the fact that he's not just lying there but deep in sleep, that state in which our identities turn oceanic and we are no longer fully ourselves. All this is compounded by the surprise that waits when you walk behind the work and discover that it's hollow-no storehouse of self, no inner workings, just a scooped-out shell of resin. And finally there is the work's title, which is not ‘self-portrait' or ‘me asleep' but rather Mask II – a title which tells us in no uncertain terms that something is being hidden by this face.