
For Scribal points, what is the wooden gadget on the table and how does it work?
Jake says, "The proverbial better mousetrap," and indeed it is since it was constructed by St. Joseph himself. It comes from the right side of the Mérode altarpiece, by the fifteenth century Master of Flémalle -- probably Robert Campin. Art historian Meyer Schapiro writes:
In the Mérode Altarpiece by the Master of Flémalle,
the figure of Joseph appears in a wing beside the Annunciation
as an artisan who fashions mousetraps.... [T]his detail of the
mousetrap is more than a whimsical invention of the artist, suggested
by Joseph's occupation. It has also a theological meaning that
was present to the minds of Christians in the Middle Ages, and
could be related by them to the sense of the main image of the
triptych. St. Augustine, considering the redemption of man by
Christ's sacrifice, employs the metaphor of the mousetrap to explain
the necessity of the incarnation. The human flesh of Christ is
a bait for the devil who, in seizing it, brings about his own
ruin. "The devil exulted when Christ died, but by this very
death of Christ the devil was vanquished, as if he had swallowed
the bait in the mousetrap. He rejoiced in Christ's death, like
a bailiff of death. What he rejoiced in was then his own undoing.
The cross of the Lord was the devil's mousetrap; the bait by which
he was caught was the Lord's death...." (Qtd. at Oneonta.edu art history website)
I don't know exactly how the mousetrap in the painting would have worked, but Paul Gans of the Medieval Technology Pages has found this description by Chretien de Troyes of a gate designed to work like a rat trap :
This gate was very high and wide, but had such a narrow
entry-way that two men or two horses could not pass through
together or meet one another in the gate without crowding
or great difficulty; for it was built just like a trap that
awaits the rat on its furtive scavenging: it had a blade
poised above, ready to fall, strike, and pin, and triggered
to be released and to fall at the slightest touch.