Leonardo da Vinci's Virgin on the Rocks before and after restoration.
The exhibition leads up to one great climactic moment, when the National Gallery's Madonna of the Rocks is shown face to face with an earlier version of the same painting from the Louvre. In the words of Nicholas Penny, the director of the gallery – and a man not given to breathless exaggeration – this is "a juxtaposition that was almost certainly not seen even in Leonardo's own lifetime, nor at any time since, and one that is unlikely ever to be repeated".
It doesn't get any better for Leonardo scholars – especially as the London Madonna of the Rocks, traditionally regarded as the inferior of the two, with fewer passages confidently to be ascribed to the master, has recently been cleaned and studied afresh. The French version, yellowed and more damaged, at first glance looks the poor relation. But then, gradually, the subtlety and softness of the Paris version begins to emerge. An ambiguity to the gaze of the angel that sits on the right of the picture, pointing at John the Baptist, but apparently looking at something that might be behind your left shoulder..
It is that ambiguous gaze of Leonardo's subjects that mesmerises in the early rooms of the exhibition. Here we are shown how Leonardo broke the mould of Milanese royal portraits by rendering sitters not in strict profile, but half-turned towards or away from the viewer..
