Between 1945 and 1975, the National Gallery issued a complete series of scholarly catalogues of its collection that set the standard for such publications. Distinguished both for their unrivalled attention to detail and for their depth of learning (the entry on Leonardo’s The Virgin of the Rocks includes no fewer than ninety-seven footnotes), they were produced under the aegis of Martin Davies, who went on to become the director of the gallery. Thirty years may seem a long time to have taken to complete such a project, but the fact of the matter is that rival institutions such as the Louvre, the Prado and the Uffizi, whose holdings are admittedly considerably more daunting in scale, have even now scarcely begun to follow Trafalgar Square’s lead.

In 1998, the National Gallery inaugurated a new and incomparably more detailed series of collection catalogues, of which this is the ninth to appear, and the third to be written by Nicholas Penny, in this case in collaboration with Giorgia Mancini. Like Martin Davies before him, Penny is an eminent