Walafrid Strabo's Glossa ordinaria cites this episode from Genesis
(where the patriarch Jacob blesses his grandsons) as a symbol of God's
favouring the Gentiles over the Jews. By crossing his arms, Jacob places
his more favoured right hand on the head of Ephraim, the younger of Joseph's
sons (representing the "younger" Gentiles) and his left on Ephraim's
older brother Manasses (the Jews). The crossing of his arms, like the
crossing of Isaac's legs in panel 5, is also another visual reference
to the sign of the Cross.
Tituli: "IOSEPH FILII ISAAC"