This painting shows Jesus slipping the Holy Prepuce onto St Catherine’s finger.
St Catherine of Siena is one of the Jesus’s 76 virgin brides. During the mystical marriage Christ appears to his bride in a vision and presents her with a ring. This is followed by a ceremony where his mother, saints, and angels are present.
St Catherine was special, not only because she levitated and was bulimic and vomited up twigs, but because Jesus gave her His Holy Foreskin to wear on her finger instead of the usual gold ring.