The 'Triptych with Scenes from Christ’s Passion' combines several scenes illustrating the story of Christ’s suffering, death and resurrection, in chronological order from left to right. The centre panel is owned by the National Gallery, London. In its original setting on an altar the triptych would only have been shown open on special religious occasions, probably during Easter week. For most of the year the two side panels would have been folded across the centre panel, concealing the central crucifixion but displaying the paintings on their reverse sides; this is the reverse of the left wing. The miraculous Mass of St. Gregory was a popular subject in the 16th century. According to tradition the great 6th century Pope, St. Gregory, was saying mass when he saw upon the altar a vision of Christ’s wounded body and the instruments used to torture him. The vision served to uphold belief in the doctrine that bread and wine are transformed into the body and blood of Christ during mass, and that the mass is a re-enactment of the Crucifixion. The right hand reverse wing of this triptych can also be seen on this website.(WAG 1226) When the triptych is closed the backs of the two side panels can be seen to represent a single architectural space.