Perhaps the most famous rendition of St. Joseph, that of the Mérode Altarpiece of c. 1425–1432 from the workshop of Robert Campin (Fig. 2.14), exemplifies early modern lay devotion to the saint and to the Holy Family. It is also a work to which we should return, for many people ask how this refined example could possibly contain humor. The answer is clarified perhaps not so much by what the work contains, but rather by the multivalent meanings produced by a possible fifteenth-century reading of its iconographic content, and how, in turn, such meanings facilitated the devotee's experience of sanctity. The experience of this work, and many such works, might be best understood as something akin to the rhetorical ductus of late classical and medieval theory, described by Mary Carruthers as ‘an ongoing, dynamic process rather than as an examination of a static or completed object.’ Ductus is ‘the way by which a work leads someone through itself: that quality in a work's stylistic patterns which engages an audience and then sets a viewer or auditor or performer in motion within its guiding structures and articulating colours.’ Replete with theological symbolism and ecclesiastical metaphor, the Mérode Altarpiece is unquestionably a highly complex, deeply meaningful work. The mousetraps, one on the table and one on the windowsill, as we learn from Meyer Schapiro, have been invested with Augustinian metaphorical meaning as snares for the devil.