The Devil's Mousetrap
The Merode Altarpiece in a little catechism waiting to be decoded
The Merode Altarpiece is a beautiful, richly symbolic Flemish triptych probably painted by Robert Campin and assistants in the 1420s on a commission from the Engelbrecht family. The name “Engelbrecht” means “brought by an angel,” which would have naturally suggested the annunciation as subject matter. The work measures about 4’x2’ and was intended for home devotional use. It’s currently housed at the Cloisters in New York.
In the left panel, we see the donors, peering through the door into the room of the Blessed Mother. The peculiar servant in the back seems to have been added later. The figures are:
Peter Engelbrecht, the Donor (kneeling in front), a wealthy merchant from Mechelen.
The Donor’s Wife (kneeling behind), probably Margarete Scrynmakere, added later, possibly after the marriage.
Servant (background) added later, possibly a self-insert by the artist, or perhaps a symbolic figure like Isaiah.
At the center is the Blessed Mother with breviary in the moment just before she notices the angel. The scene is a hortus conclusus (enclosed garden), symbolic, along with the lillies, of the Virgin Mary’s purity. A book and a scroll are open on the table: the New and Old Testaments, with the New atop the Old. The table has 16 sides, suggesting the prophets of the Old Testament. The cloths with blue stripes may be meant to suggest a tallit.
The scene is notable for the absence of any typical symbolism of the Holy Spirit, such as a dove. Instead, we have an unusual little sprite flying downward on a beam of light holding a cross. The soul of Christ at the moment of the incarnation flying to the womb of the Blessed Mother?
Is the recently extinguished candle a sign that the light of the Holy Spirit is already on the move? And why is one candle missing from the mantle?
Mary sitting on the ground in a gesture of humility, but resting on a bench marked with lions, suggesting a throne and thus signifying her Queenship. The lions themselves suggest the throne of Solomon, seat of Wisdom, which Mary does not occupy but, nonetheless, rests upon.
The right panel is even more interesting. It shows St. Joseph at his workbench, and his presence in this domestic scene is unusual.
Nails, a hammer, saw, pliers, and drills all refer to the building of the cross, the crucifixion, and the tortures of Christ and the martyrs. The board Joseph is drilling may be the strainer for a wine press, and thus symbolic of Christ’s blood.
A completed mousetrap is on the table. This is almost certainly a reference to a theme Augustine used: Muscipula diaboli, crux domini--The Lord’s cross is the devil’s mouse trap.
This is sometimes translated fly-trap, but it’s probably more precise to call it a “baited trap,” or a trap baited with flies.
Augustine:
Let no one, therefore, deceive you, when you are perhaps annoyed at flies. For some have been scoffed at by the devil and caught with flies. Fowlers, as you know, are accustomed to put flies on snares to deceive hungry birds; so, too, these men have been deceived by the devil with flies.(1)
The connection between evil and flies gives this added resonance. The Philistine deity Ba’al Zəbûb is literally “lord of the flies.” The New Testament refers to Beelzebul as the Prince of Demons.
Also:
The Devil exulted when Christ died, and by that very death of Christ the Devil was overcome: he took food, as it were, from a trap. He gloated over the death as if he were appointed a deputy of death; that in which he rejoiced became a prison for him. The cross of the Lord became a trap for the Devil; the death of the Lord was the food by which he was ensnared. And behold, our Lord Jesus Christ rose again. Where is the death which hung upon the cross? Where is the reviling of the Jews? Where is the pride and haughtiness of those who shook their heads before the cross saying: ‘If he is the Son of God let him come down from the cross.’ But He did more than they demanded in their revilings, for it is greater to rise from the tomb than to come down from the cross. (2)
See also, Ps 124:7: “We have escaped as a bird from the snare of the fowlers.”
This is a catechism in images, and there’s a lot more to unpack. Its most striking feature is the way it draws Joseph into the story as an active, rather than passive, figure in our salvation. Joseph is the craftsman making the trap Jesus will use to snare the devil.
Augustine of Hippo, Tractates on the Gospel of John 1–10, ed. Thomas P. Halton, trans. John W. Rettig, vol. 78, The Fathers of the Church (Washington, DC: The Catholic University of America Press, 1988), 53.
Augustine of Hippo, Sermons on the Liturgical Seasons, ed. Hermigild Dressler, trans. Mary Sarah Muldowney, vol. 38, The Fathers of the Church (Washington, DC: The Catholic University of America Press, 1959), 392–393.
The famous “mousetrap” in the Mérode Altarpiece may not be a trap in the literal sense. Saint Joseph is not constructing a device to catch, but rather working on a wooden panel—pierced, structured, almost like a grate. This same lattice-like motif quietly recurs throughout the scene: in the bench, the furnishings, even the window of the Annunciation.
What if this visual pattern points to something deeper? A theology of concealment.
In the Gospel of Matthew the Evangelist (cf. Mt 13:57), the “scandal” of Christ’s ordinary origins is emphasised—yet Matthew is also the evangelist who most insists on the marriage of Mary and Joseph. That marriage becomes, in a sense, the true “trap”: publicly visible, even exposed, leading all to assume a normal human origin.
But this apparent normality is precisely the velamen—the veil. As several Fathers suggest (notably Jacob of Serugh), Joseph stands as a covering presence, shielding the mystery until the appointed revelation. The marriage (maritalis species) is not incidental; it is providential.
God, in His “marvellous economy,” chooses not to remove scandal entirely, but to redirect it—concealing the divine origin so as to prevent a greater rejection. The lattice, the screen, the humble carpentry: all seem to echo this logic of protection, mediation, and delay.
Is it known if the overall concept and source of the symbolism is Engelbrecht, the artist, or a collaboration?