I came across this French Christmas carol and it made me ponder the symbolism of ox and ass  in a nativity scene. It is said that the ox knows it’s owner and the ass knows it’s master. Words coming to mind are strength and resilience, patience and humility. The ox dragging the plow and the ass carrying the load.  Farm animals both of them, indispensable for  people to till a field and bring the fruit of their labour to others.

Or what do you think ?

Lorenzo Monaco "Nativity" (ca 1405) Metropolitan Museum of Art

Entre le boeuf et l’âne gris