This is Robert Campin's most famous work of art called, The Merode Alterpiece or the Annuciation. A brief discription: the left panel represents Isaiah as he wrote in Isaiah 10 of the coming Christ. The center panel is Gabriel announcing to Mary that she would be the mother of Jesus. Look around the room in this section and you will notice many symbols of the virgin mother, the Jewish heritage, the Lion of Judah, the baby Jesus floating from the oculus window carrying a cross and a few others. The right panel is Joseph at is carpentry work. In the lower right hand corner are the tools which sybolize how Jesus will die and are referenced in Isaiah 10. The mouse trap in the window symbolizes the trap Satan would fall into (by his own deception) with Jesus as the bait. If you have a chance to look up more about this painting, you'll find it interesting too, Enjoy!