The Merode Altarpiece 

The Merode Altarpiece is a triptych created by Robert Campin. The piece is on a three part panel, and was created for private use, seeing as the painting is relatively small being 64 x 63 cm and each wing measures 65 x 27 cm. Many believe that this piece is a copy of the original created by a follower of Robert Campin's so its currently described as being created by "Robert Campin and assistant". Even still its considered to be one of Campin's greatest works of art. The portraits of the donors are in the left panel; the figure of the female donor, and the servant behind her.The discovery of additional layers of paint has led to the conclusion that the donor's wife and the man at the gate were added at a later stage. X-rays of the left-hand panel indicate that the identity of the artist of this part is more likely to be Rogier van der Weyden, Campin's most gifted pupil. In this scene the patrons of the altar, Peter Engelbrecht and his wife, are depicted, kneeling devoutly, along with a man standing by a gate in the background.

The subject of the Altarpiece is the Annunciation, which is shown in the central panel. The central panel is a great example of an artist creating a work of art that is the "precision of the moment". It depicts the moment right before the angel Gabrielle tells the Virgin Mary that she will be the mother of God's son. As the painting so elegantly shows you, Mary is so engaged in her scriptures that she doesn't even notice the Angel sitting in front of her, she doesn't even pay mind to the wind that just blew the candle out signaling God's presence. The central Panel is most famous for its "domestication and naturalization of the sacred". Anybody, at the time this painting was created, could identify and even relate to the Virgin Mary because of how close the scene looks to their own home. They can imagine the shock or surprise she must have felt when she finally looked up from her scriptures. This touch many people's hearts because such a scared and definable moment in history is something they could feel so close to.

The right wing depicts Joseph at work in his carpenter's shop. The objects in Joseph's workshop are chosen so as to symbolically prefigure the Passion: the sword-shaped saw in the foreground alludes to the weapon that St Peter would use to cut off Malchus' ear while Christ was being arrested; the log that lies nearby recalls the wood of the cross; the stick propped against it, of the crown of thorns; nails, hammers, pliers and screwdrivers all prefigure the instruments of the Passion. The mousetrap which Joseph is making may be a reference either to Christ's arrest (the mouse being associated, in popular tradition, with the soul) or to the Augustinian doctrine that the Virgin's marriage and Christ's Incarnation were planned by Providence as a trap in which to catch the devil, like a mouse lured by a bait.
Sources:
http://en.wikipedia.org/wiki/M%C3%A9rode_Altarpiece
http://www.wga.hu/tours/flemish/flemalle/index.html