Renaissance to Goya: Prints and Drawings from Spain, British Museum, London

This is an exhibition driven by pedagogues. Its purpose is to show us a range of drawings and prints from the various regions of Spain between 1662, when Philip II made Madrid his new capital, and the death of Goya in 1828.

It takes us on a journey of evolutionary discovery, partially dictated by chronology and partially by geography. We go through it dutifully, glazed cabinet by glazed cabinet. Given that we are making this immense voyage in the Prints and Drawings Room of the British Museum, each artwork is never more than a foot away from our eyeball, so off we go, admiring preparatory drawings for the grand decorative schemes planned for the Escorial, scrutinising a putti's sky-flailing foot here and a capuchin's hood there.

Many of these prints and drawings are very good indeed. Unfortunately, they are not quite works of genius. We know that they have set the exhibition's curators alight though because the exhibition is accompanied by a house brick of a catalogue which might have been much shorter.

And then, at a certain point, something marvellous happens. The year is 1762. The Tiepolos, father Giambattista and his two sons Domenico and Lorenzo, have just arrived in Madrid from Venice.

The sheer brilliance of their etchings takes Spain by storm. We stare at one here, by Lorenzo, of St Anthony doing a miracle on an irascible son. This is not the first time that this subject has been treated in this show, we remember - Esteban Murillo tackled the same alarming theme.

The son has insulted his mother and, full of remorse, hacks off one of his legs. St Anthony restores it. The Tiepolo version is full of loomingly dramatic contrasts of light and dark. We see the partially severed limb. Murillo smooths it away. He is too sweet to want to shock us.

Then, alongside the brilliance of the Tiepolos, come other great practitioners – it all seems to happen in the last third of the show, after we have almost been lulled asleep – Ribera, Zurbaran and, greatest of all, selections from various suites of etchings by Goya, who is so wild and untrammelled and no-holds-barred emotionally that it is sometimes quite difficult to look without wincing.

Here is greatness indeed, and especially in 'Bulls of Bordeaux', a sequence of late etchings devoted to the bullfight, the roughly rendered, repulsively exhilarating savagery of it all caught on the wing by a very old man who, like Hockney, was profoundly deaf.