MADRID.- The exhibition "Contexts of the Permanent Collection 23" presents an overview of selected works in grisaille, a technique which experienced its heyday in the 14th and 15th-centuries and was highly popular in the Netherlands. Among the great masters who practised the art of grisaille was Jan van Eyck, and his famous "Annunciation Diptych", owned by the Thyssen-Bornemisza Museum, constitutes the focal point of this exhibition. Jan van Eyck (Maaseick, c. 1390-Bruges, 1441) is a central figure in the history of art. The beginnings of the career of this accomplished manuscript illuminator