Great Works: Bust of a Laughing Boy, by Desiderio da Settignano

Kunsthistorisches Museum, Vienna

We seldom associate the idea of the marble portrait bust with spontaneity. The material itself seems almost to work against it. To memorialise in marble is not to be engaged in the capturing of something fleetingly natural, but to set up and apart, to commend and cause to survive, qualities of the person that deserve to survive and to be commended for that survival – endurance, nobility and beauty, for example.

In short, the portrait bust has so often been an exploration of the nature of solemnity. What is more, it is unusual to find an early sculpture of a child that appears to be doing nothing but showing off the nature of a child – not just this child but any child – at the age of three or four. When we see children at all in the art of these times, we are more accustomed to looking at them in various supportive or symbolic roles – as cherubs, putti, small-scale angels or other species of sacred image, for example.

And so here is something quite shockingly different. It is a work in marble that appears to exist to show off, with no small degree of indulgent tenderness, the way that a child behaves when he has been caught off guard. Yes, this sculpture looks as if it is an astonishingly pleasing variant upon another that might well have looked much more official, had something not happened to cause the child to be distracted by a look, a gesture, the agitation of a toy, the sudden flight of a bird... We feel on our pulses that it is something exquisitely accidental, a moment caught – that sudden swivel of this child's head to the left, captured, frozen here, quite by accident, on the wing. And yet that simply cannot be true, can it? What child of this age could have been cajoled into posing for a bust such as this one for the length of time that it may have required? Children simply do not do that sort of thing – or do they? Which leaves the mystery of the pose unsolved. We probably have to accept that Desiderio caught this likeness in some way, but how? Even to draw the child, repeatedly, and then to work up something as humanly credible as this from those drawings, must have been so difficult...

It is that swivel that so delights us. To pose face forward is the more customary way. To pose face forward can often indicate steadfastness, dependability, sureness of purpose, the promise to deliver upon one's pledges. It would surely be the favourite pose of an airman, a politician and a football manager – indeed, just the other day, I saw an image of a bronze portrait bust of Arsene Wenger by Etienne Millner. He was looking fiercely ahead. Looking askance in the way that this child looks askance, on the other hand, is to throw off all those suggestions of certitude. Humour, flightiness, the possibility of doubt or changes of mind enter into the picture. And what of this mouth, the way that it is open? Bernini, another great portrait sculptor, once said that to inject a work with that vital sense of animation, you need to ensure that the mouth looks as if it has just been uttering words – or as if it has just uttered words. A slight hint of openness then.

There is much more of a hint of openness here though. And yet this opened mouth has nothing to do with the voluntary act of speech, we feel. It is not even the openness that we would associate with a cry. This hanging open is surely an involuntary gesture, of surprise or delight or amazement, and when the mouth yawns open like this we see those marvellously credible small child's small teeth and more than a hint of a peeking tongue – like a lizard about to emerge from a dark overhang of rock. What is more, letting the mouth fall open in this involuntary gesture of spontaneous delight has caused this prosperous child's cheeks to puff out. The head looks so beautifully compacted, capped by that tadpolish swim of wavy hair.

Why is it that this portrait bust has an unusual degree of human credibility? So many portrait busts do not. They look like ghostly embodiments of the noble mind. The reason is surprisingly simple. It is because the skin of a child, its smoothness, its delicacy, its lack of wear and tear, is much closer to the texture of marble than the skin of a mature human being. And this sense of the truly credible is intensified, made more so, by the way in which the child's garment has been made to fall away to reveal those gleamingly small shoulders.

About the artist: Desiderio da Settignano (c1430-64)

Born into a Florentine family of carvers and stonemasons, Desiderio da Settignano was a sculptor whose work was greatly influenced by Donatello. Scholars have even argued that he may have been Donatello's pupil. Greatly admired by Leonardo, his works, which include a number of portrait busts of women and children, possess an unusual degree of tenderness. One of his finest achievements is the tomb of the humanist scholar Carlo Marsuppini.