Interior: saints Agatha and Claire / Exterior: The Annunciation: Mary

This altarpiece panel with Saints Agatha and Claire on the interior and the Annunciation on the exterior, dating to around 1480, demonstrates the dual function of Flemish altarpieces as devotional objects operating on two registers. When open, the saints intercede for specific devotees—Agatha for protection against fire and breast diseases, Claire as Franciscan patron. When closed, the Annunciation on the exterior grisaille panels presents the scene of the Incarnation, reminding worshippers of the theological mystery celebrated within. The gray tonality of closed-wing grisaille was itself theologically significant, mimicking stone sculpture and acknowledging the painting's material status as representation rather than presence.

The interior saints and exterior Annunciation demonstrate Bouts's ability to work in different registers — the colorful interior panels contrasting with the more restrained grisaille or painted exterior that was revealed when the altarpiece was closed.