Variations on a lucrative theme, reliably commissioned again and again from Giovanni Bellini (1430-1516) during his extremely long Venetian career. My current reading is a tremendously learned and amusing book by Robert Harbison called Reflections on Baroque. In it he makes a passing reference to the supporting babies or children (generally equipped with wings or halos) in Renaissance painting as "visitors from another sphere" (contrasting this to their merely decorative function in the Baroque and Rococo painting and architecture of later centuries). They are certainly "visitors from another sphere" in the standardized image (monotonous, yet never inauthentic or dull) that Bellini assembled here.